I too have recently been interested in TeX and Rust. Apart from Tectonic (wrapper around XeTeX and dvipdfmx) and the attempt to rewrite it in Rust (your first link), I also found [1], an attempt to rewrite TeX itself in Rust. I also understand that you are a supporter of the Tectonic in Rust effort, so hopefully you can fill me in on the current progress.

At first I though that just rewriting XeTeX/dvipdfmx in Rust just for sake of being written in Rust was foolish, because of TeX's untypical memory model. Also because of the manual translation using c2rust (also on C code generated from Pascal code that uses a lot of macros).

But after lookin at it now it seems that the rewrite progressed and the result are parts looking very Rusty, which is nice.

I too had ideas about TeX in Rust, but I think that starting with LuaTeX would be much more beneficial. Apart from LuaTeX having obvious support of scripting in Lua and being very extensible, XeTeX has other disadvantages. See for example [2], which still in my opinion misses many internal differences, where LuaTeX is much superior.

Do you have any tips on how to join the Tectonic / TeX in Rust community? Where can I potentially discuss my foolish TeX/Rust ideas, being very new to Rust?

[1] https://github.com/crlf0710/tex-rs [2] https://tex.stackexchange.com/a/593217/125126