motivated by the recent top post on longevity tips for a Pi[1], I'd like to know what you are using it for.
I myself use one as a NAS to store personal documents. It runs Openmediavault[2] to provide a SAMBA share. Once per day, it runs a backup[3] to a 1 TB cloud storage[4], which itself comes with automated backup snapshots.
[1] https://news.ycombinator.com/item?id=39407631
[2] https://www.openmediavault.org/
[3] https://www.borgbackup.org/
[4] https://www.hetzner.com/storage/storage-box/bx11/
In the end, though, they were a pain to manage. I run Archlinux on all my Linux systems, and while ArchlinuxARM exists, it feels like the project is running on fumes. Packages were falling out of date, and I kept running into issues where a given feature would only work with the forked linux-rpi kernel, or the linux-aarch64 kernel, or one of them wouldn't boot, etc.
I ended up buying a pile of refurb Lenovo mini PCs from Amazon. I now have a stupid number of boring USB keyboards that I'll never use, but the mini PCs work great, and they're Intel chips so I can just install regular Archlinux.
I have one remaining Raspberry Pi: I needed something that supported USB-OTG to fake keypresses for my KVM. The KVM supports receiving keyboard shortcuts (It's something nuts like alt-printscr-$digit) to toggle between inputs, but using the special "keyboard" port for my USB hub w/ keyboard/webcam/etc caused issues.
So I have the Raspberry Pi plugged in there. It pretends to be a keyboard, and runs a simple web server that receives API requests and triggers the right hotkey.
One day I'll find a better way to deal with this, because right now that system is very very bespoke and unloved.