Thanks all for your comments and answers, I’ve just tests the keyboard and it seems to work pretty fine, I’m really happy, I didn’t expect to get something working directly!
As a reminder, here is the commands I’ve used to get the firmware to copy:
# Install the required compiler
sudo apt install gcc-arm-none-eabi
# Enter in the virtual environment
. ~/.virtualenvs/qmk/bin/activate.fish
# Check the keyboard
qmk list-keyboards | grep sofle
# Check the keymaps
qmk list-keymaps -kb sofle_choc
# Compile
qmk flash -kb sofle_choc -km via -e CONVERT_TO=promicro_rp2040
I've also ordered a sofle choc v3 and started to use it, but I didn't soldered the led or the screens yet. I'm also happy with my keyboard and the delivery was done properly !
As a minor point I'm not sure if the sources for the keyboard have been published yet (the fork in the repo haven't been updated since a lot of time, and I didn't found a v3 branch). This is not a problem for me but can be if you have foss vibes.
I've also removed the bottom plate because it make the keyboard sound... oddly when you press a key. I have to make some tests with plasstics screws instead of the metal ones given in the kit.
Otherwise, I'm very happy with the keyboard, comming from a typematrix I've been able to use it as soon it was flashed !