No love for Turris? They’ve basically just added an easier web management UI alongside lUCI and their devices are specifically designed to run OpenWRT. Also they’ve sent a fair amount of patches to upstream (search the OpenWRT git repos for authors with @nic.cz email addresses)

https://turris.com/

Unironically this. Also Juniper Junos.

How about both?

Regardless of configuration, you still need to access the instance from mastodon.mydomain.tld or lemmy.mydomain.tld, but you can configure the Mastodon to use @mastodonuser@mydomain.tld as its identifier by setting WEB_DOMAIN to mydomain.tld.

Mastodon documentation on the topic: https://docs.joinmastodon.org/admin/config/#web_domain