This is primarily oriented toward building AURIX TC3xx firmware using freely available tools. I have a few blog posts on this.
What I found so far:
I've been able to build a few of the Infineon "example" projects from the github repo, create a Makefile for them and build them cleanly with gcc-11. They run correctly on a TRC375 dev board.
This is a work in progress. I'll make updates here.