The 3d acceleration work from Hamish Morrisson is on Gerrit, the fatelf work isn’t because there is no interest from anyone else in the team (we don’t want it).
The other things you mention are too vague for me to say anything specific, if what you have in mind is the crypto kit, that’s also on gerit. Likewise for Jaroslaw’s early work on arm64 (which broke other platforms and ignored the coding style, but evetually we extracted, cleaned and merged the relevant parts)
There is also the bfs partition resizing code on gerrit. Waiting there for a few years.
No one seems interested in testing, improving, or reviewing any of this code which is very easily available. I do rebase it from time to time and checks that it builds.
If there are other things we have missed, we can add it to gerrit very easily (anyone can do it as long as they have a github account). I still don’t think putting all this abandoned code in a single branch is going to do us any good.