Okay, I finally did this, after 2.5 month of preparation, finding the parts and reading all tutorials. So first to say, it's not the easiest thing because there are a lot of small things to bear in mind.
For the left hand drive, and for whatever reason, the Connects2 kit was almost 2x more expensive everywhere I checked. For ex., it was 250 Euros in my local car audio shop. There was a listing on Amazon for around 80 Euros, but after 10 days all the stock was gone. After weeks of searching, I finally found this one:
https://caraudiocenter.se/product/installations-kit-honda-civic-kombi-06-lhd-ctkhd01l/ 1200 SEK (104 Euros). Had some luck because my sister lives in Sweden so she shipped it to Croatia. They might have International shipping available.
For the head unit I went the similar way as OP. There is an eBay reseller for Atoto in Germany (Atoto De) who sells second hand units. You can even place "best offer" bid. Ended up with Atoto F7 WE (wireless edition for Android Auto and Car Play) for 130€. Package arrived in 5 work days and the only thing missing was screen protector. There wasn't a single scratch anywhere on the unit and it seemed new to me.
First mistake I made was during the patch lead crimping. After consulting to the manuals, I took the ISO A harness out of the box without looking and started crimping splice connectors. Connected KEY 1 to steering wheel key#(+), KEY 2 to steering wheel key(+), GND to swc-gnd, and blue wire from antenna adapter to power antenna.
Plastic removal tools are really handy for the trims, there are sets for around 20€ (purchased mine when had boot leaking issue). Followed the Youtube video from this thread, center console removal was relatively easy. There are 4 screws and also 2 plastic pins (1 for each side, or so I thought). Don't use the plastic removal tool here, you should use a screwdriver to push the pin inside and then they're easy to remove.
Then I made a second mistake. Started removing center console plastic below the OEM unit but it didn't budge from one side. Clips right below the OEM unit were relased, but the left part of the trim was still in place. It appears there's a 3rd plastic pin just next to the accelerator pedal. The triangle bit above the stereo demands a lot of patience to remove without breaking any clips.
Supplied plastic fascia isn't the best, it's thinner than original and when unit is assembled, appears very flimsy/wobbly. Plastic side brackets also don't give too much confidence. Process of removing the air vents from the OEM stereo is not straightforward. One of the forum members posted really neat trick few years ago - wooden "kebab" sticks (skewers?). You need 2 for each clip (8 total), once lifted, it goes out without a problem. Metal fasteners/clips are also pain to remove and need "heavy" lifting from both side with couple of screwdrivers.
When connecting cables, patch lead (one with the steering controls) goes into the black box first, then the other end of this cable to the stereo. Then the bigger harness from the kit goes to the other side of the black box. After that you need to connect ISO plugs, big cube connectors with four rows of pins one to another. In the end you should connect grey and green cables.
AC screen worked immediately after the ignition key. Unit booted up, the steering wheel controls in the unit settings worked fine. You need to bind the steering wheel controls to unit functions since it's not out of the box for Atoto. Set the time both on AC screen and the unit, saved some radio stations. Wireless Android Auto was fine, but wired connection didn't work. Turned off the ignition keys thinking everything is fine and I started messing with the USB extension and arm rest console. Turned the ignition back and noticed the time was out of sync - AC display was OK, but not the unit. It started where it left off. Also button mappings for the steering controls were gone and so were the stations. Then it hit me that I might used the wrong cable after all.
Disassembled everything, connected cables to ISO B harness and tested again. Everything worked, but this time no steering wheel control. AC screen still works, you can set time with buttons, but there is no input in the head unit settings. It seems there are 3 more ways you can connect the patch lead to Chinese brand units. So i just swapped KEY 1 to steering wheel(+) and KEY 2 to steering wheel#(+). Also ditched the splice connectors while figuring this out - WAGO clamps are great for this. To reset the black box, leave it 5 minutes disconnected (but 30 seconds probably works fine). Connects2 has great support service, they are really fast and responsive and their very first suggestion worked.
Hoped it was only on the right hand drive cars, but the fascia doesn't go all the way through on left hand side either, need to remove half a centimeter of plastic dashboard inside the bottom right part. There are no screws at the bottom like on the OEM unit, so center console removal probably won't be necessary in the future to pull the unit out. To my disappointment, USB extension cable is not long enough to be routed to the arm rest cubby. Instead I put it in the small compartment beneath the head unit, together with wireless antenna. Not the ideal, but it'll do.
The last hardware issue - wired Android Auto didn't work. Tried 3 different cables, but in they were all off brand. Purchased genuine Huawei and Samsung USB-A to USB-C cables and they work perfectly. The only software issue I discovered is low navigation voice for Waze and Maps. While FM radio or Deezer is on, I can't hear it. The sound goes lower for the music, but nothing can be heard regarding navigation. Didn't solve this one yet.
The head unit is really good BTW, screen is bright enough, touchscreen and UI responsive, didn't notice any issues so far, except the navigation voice volume. And there is also the price.
Thanks OP once again for the idea
