To further simplify.

For step 1+2 , the router might have a built in DNS resolver which would eliminate the need to maintain another container or service.

For step 5, depending in the router software, with a single target (e.g. a nas running docker services) you might also be able to add a wildcard rule to catch any query for *.local.domain.com to resolve to that machine. This would simplify adding things in the future as the only thing remaining would be the caddy config.

Well, at least they tell you to not trust it for production in it’s current stage I guess.