Nextcloud data daily, same for the docker configs. Less important/rarely changing data once per week. Automatic sync to NAS and online storage. Irregular and manual sync to an external disk.
7 daily backups, 4 weekly backups, “infinite” monthly backups retained (until I clean them up by hand).
I use both, Traefik on my docker host that’s also used for trying out new stacks, and NPM at work for a config that won’t change (ever, probably).
Yes, the NPM web ui is somewhat easier in regard to proxying targets outside Docker.
Going container-only on a Debian base is a very stable environment without filling up your system with leftovers from experimenting with new services.
And yes, Jellyfin runs fine in a container.