I resurrected some of my old code for computing hash collisions: https://github.com/DavidBuchanan314/birthday_party (it's actually more of a rewrite)

It can collide 96-bit truncated sha256 in under 24 hours on a 6700XT.

Next steps are a) figure out something interesting/useful to do with it (beyond surprising people), and b) modify it to support accepting contributions from untrusted clients (see "Future Ideas" in README). For a sufficiently interesting answer to a) I could create a "SETI@home"-like system.

A ~102-bit collision would cost $$ worth of rented GPU capacity, and 128-bit is optimistically possible with enough crowd-sourced compute (a ~5-figure dollar cost if you were renting).