I’m in the same boat. Would be good to have the ability to have a single identity that works across the fediverse. As a first step if you have your own domain anyway, it’d be cool to alias that to different underlying Mastodon/Kbin/Pixelfed/etc. accounts. It’s possible to some small extend using the “Webfinger” protocol: https://philna.sh/blog/2022/11/23/alias-your-mastodon-username-to-your-own-domain-with-jekyll/