Since SSDs and then NVMe drives have been a thing, I’ve been adding noatime,nodiratime to the relevant partitions in /etc/fstab
This prevents times from being written for every file or directory access.
Also as physical RAM has increased, I no longer create a swap partition.
For something like mysql replication, you may want to exclude logging tables or other tables that are continually updating.
Speaking of logging, you may wish to have logs on a ramdisk rather than writing to the NVMe.
Alternately, the highly transactional data could be written to SD card, whereas the NVMe drive houses the OS and less mutable data.
You may also find the smartctl or nvme commands offer some deeper insights into the status of your drive.
I add fstrim to /etc/cron.weekly for drives that support/need it.
As for the CPU fan, I initially plugged into 3V/gnd but after putting the rock5 in a case, I moved to 5V/gnd. For my use case, the fan is quiet enough to run all the time and I’d rather have the cooling than use a fraction of a W less power.
You may wish to monitor and compare temps with the fan sucking vs blowing to see which is better for your env.
Hope this helps!