Here is a recent blog post where somebody tried to install Debian on an Amiga 4000 with an 68040 running at 25 MHz.

https://sandervanderburg.blogspot.com/2025/01/running-linux-...

I didn't find what Debian version they tried but I think it's implied it's a recent version. They ran into memory issues. They had only 48MB while the recommendations are to use 64MB. It did boot though until it threw errors because of memory constraints.

They got a working system by trying Debian 3.1 though.