"This guide details hosting the Lemmy backend and frontend on different domains. This is useful, for example, if you want users to have a webfinger (user handle) without a subdomain, but want to host services on the same domain."
https://join-lemmy.org/docs/administration/separate_subdomains.html
(1/2)
#HatTip to @LaurensHof for the link to the Lemmy update.