I haven’t tried it myself but Mattermost offers most of what you’re looking for.

https://github.com/mattermost

Can you do a speed test of your zpool?

dd if=/dev/null of=<mount-point>/test.file bs=1G count=10 status=progress

I use Standard Notes

Did you try S3 sleep?

More info here: https://wiki.archlinux.org/title/Power_management/Suspend_and_hibernate#Changing_suspend_method