Instead of/In addition to Twitter, add the field "Federation" to insert an optional handler for distributed social network, e.g. @username@domain.tld (handlers are standardized [*EDIT: see note]).
itch.io has an account too: @itchio@mastodon.social. Several protocols and software here. Further info on current nodes here: https://the-federation.info/
Here follows a possible "Setting" interface:
and here a possible user "Profile" page:
[EDIT, technical note]: I read the comment here and thank the author. In short, AFAIU: the username@domain.tld handler (w/o leading @) is standardized per ActivityPub (the most diffuse protocol). Other protocols might use a different special character instead of @. That can be easily parsed. Also relevant for implementation: «The ActivityPub spec doesn’t cover profile discovery [, h]owever [m]ost current implementers have integrated Webfinger 5 for that purpose, since users like to work with handles rather than URLs.» In the same comment, there is a suggestion for acct-to-uri conversion via Webfinger to preserve the handler abroad diverse protocols.