How often is on-chip flash written to typically?
In addition to config/settings, it appears to be saving node list, any received messages, and GPS position updates if active.
Does nobody know how often flash is written to, even roughly?
Is it once an hour, once a minute, once a second?
Once a minute, 24/7 might mean an ESP32 could last <3 months.
As you pointed out in the original post, it really depends on how often you change settings, how often you find a new node, etc. Most writes to flash can be found here.
For ESP32, LittleFS is used as filesystem, which does some wear leveling, see: littlefs/DESIGN.md at master · littlefs-project/littlefs · GitHub. Meshtastic is about 4 years old now and I’ve not yet heard anyone wearing out their flash.