I run openHAB3 and a Phoscon RaspBee II on the same Raspberry Pi. I figured out that the file ~/.local/share/dresden-elektronik/deCONZ/zll.db is continuously written (at least every minute!). A moved this directory to zram in order to protect the SD card. Hopefully this won’t be a problem in case of a power outage! But I’m confident that this was a good decision.
I also use a RaspBee but on a dedicated Pi with the Phoscon Image. That works fine since two years or so.
I’ve added that to openHABian.
While there is a risk, it’s not larger than it already is with JSONDB (i.e. OH config) being on zram, too.
Take care of properly setting up your backup to mitigate.
I have seen that the function is now integrated in openHABian 1.7.4. Is there a way to move the deCONZ database to zram if you already have deconz installed with a previous openHABian version?
Just as the OP says, move it somewhere on zram and replace with a link there. At your own risk.