I follow this tread for the latest https://modwiggler.com/forum/viewtopic.php?p=4084568#p4084568
Good thing is depending on the builder you can swap out 3 for 4 on most uO_C.... so, get what's avialable and you should be able to upgrade (getting much easier thanks to the community becoming active again) once the new code comes out. There's a video on youtube showing you how.
Teensy 4 code is still in the works for Phazerville (beta is avialable). Squares and Circiles is working on 4 though. There is also new HW being developed for 4... that maybe ready early 2024... which is very exciting.