Just wanted to share my experience with an old Raspberry Pi 1 B.
Tried OptoPi image but couldn´t get OctoPrint to run, so I installed Rapberry Pi OS Lite 32 bits (use the default pi user and set a password you can remember, don´t ask...), ran raspi-config to set overclocking to the maximum, and then installed OctoPrint following the site steps for a manual install. Disabled the modemmanager service, added pi user to tty, video and dialout groups and made Octoprint to be executed on boot. Rebooted, added the shutdown and restart sequences in Octoprint configuration to be able to shutdown and reboot from the web interface, added the "Bed Visualizer" "BL Touch" and "Dashboard" plugins, disabled everything that wasn´t essential, rebooted just in case and started to print.
The Rpi1B while printing is running at 60 degrees Celsius with an ambient temperature of 17 degrees Celsius, CPU utilization peaks below 70% and goes like a champ. We´ll see how temperatures get with max overclock when the summer comes, worst case will have to lower the overclocking a notch or two.
Power consumption peaks at 0.70 Ah at 5.2V from an el-cheapo USB power brick.
