I've seen failure rates of >5% / year on 24/7 read-only Pi deployments across a variety of name brand consumer microSD cards. Are you getting better reliability than that? What cards have you deployed the most of?
We have a lot (upper hundreds) of the Canvas Go! Plus cards from Kingston. I'll see if I can get some more details. Basically any UHS 3 or better card our supplier can provide. A little over 300 of the Samsung EVO Plus cards.
Would love to hear more details if you can share them!
Did those have log2rak installed with a sensible size ram drive /var/log?
Logs were written to a ram fs. We experimented with occasionally flushing logs to disk, but ended up disabling this and leaving the microSD card filesystem read-only 100% of the time.