ah this is something i’ve done a few times - it’s pretty easy actually
process is more or less:
turn off akkoma - systemctl stop it (or however you run it)
make a database dump. pg_dump is your friend here - pg_dump -d akkoma -Fc -f akkoma_backup.sqlor similar will serve you well
transfer files. copy over your entire akkoma directory, the backup file, and any external directories (like uploads if you put them anywhere non-default)
== change hosts here ==
restore backup. inverse of above. pg_restore -Fc -d akkoma akkoma_backup.sql
open up your config file and correct any paths that changed in the migration. if you’re still at like /opt or wherever then this should be fine
basically do the install process again but don’t bother setting up the database, you’re good