https://basicengine.org/git_builds/rpi4_lt/
That should work on the 400 as well.
Might want to wait until the next (Jan 5) build, though, there is still a fix for screen artifacts in the pipeline.
I would have gotten that out before Christmas, but I had to order an RPi4 first. (I'm not getting another 400, it's ridiculously expensive here.)
Then I had to order a cable. Because Micro HDMI. Of course.
Then the temp they hired to deliver packages for the holidays sat on the cable for a week.
Then my backup cable arrived from China (always need to have a plan B), and I got that thing out in half a day.