No, the ports expire, but you can script the renewal / new port process via their API. I want to set up a job that gets a new port like 1x per week and tells it to the applicating using the port. Haven’t done that yet. So far my port stayed active for like a month.
With restic you can pipe to stdin, so I use mysqldump and pipe it to restic:
mysqldump --defaults-file=/root/backup_scripts/.my.cnf --databases db-name | restic backup --stdin --stdin-filename db-name.sql
The .my.cnf looks like this: