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)