I unfortunately don’t have an answer to your question @svinozhop , but since I started this thread I do want to say that I did manage to connect my ELRS receiver to the pixhawk 6c I have. In the end I also had a problem with binding, for which I opened another thread here. Finally I concluded in the other thread all the steps that I took to bind and connect the elrs receiver to pixhawk and ardupilot.
Thanks for all your help here as well, and good luck to @svinozhop