Comment by fiscalnonsense

In active use:

retropie - pi3b+

gps based ntp (2x pi2 + gps hats. Chrony rocks.)

rtl_433 monitor for 915 and another for 433 (2x pi2, 2x rtl-sdr sticks)

an ads-b 1090 monitor (pi3 + rtl-sdr stick)

libreelec - plex clients (2x pi4 (1GB and 2GB)

an emulated macintosh (pi3)

a flood monitor in the basement (pi1)

an aarch64 dev platform (cm4-8GB) and another (pi5-8GB)