What...why? You only need one account. You have the ability to join, read, and post on any other federated "magazine". The only caveat is if a site decides to break their ties like beehaw.org did from Lemmy.world until the latter got their bot situation/login guardrails in place.
The easiest way IMO is to just subscribe to other communities(make sure you search 'all' communities instead of 'local'. )
If you're using a web browser(mobile or desktop) if you're looking for a specific community you can just append it to the end of your home url if the above solution isn't working for whatever reason but I wouldn't expect anyone would need to manually type out these urls.
Example:
https://lemmy.dbzer0.com/c/(community)@[instance] - this is not a working site just a reference
so the following links all end up on the same technology community on beehaw.org:
::: spoiler open me
https://beehaw.org/c/technology
https://lemmy.dbzer0.com/c/technology@beehaw.org
https://lemmy.world/c/technology@beehaw.org
https://kbin.social/m/technology@beehaw.org :::
The only confusing thing that I think may get people is if they create accounts on both Kevin and Lemmy and start getting confused by magazine vs collection(essentially subreddits or /r/ from reddit)
Also maybe, why does data such as upvotes, user's subscribed, upvotes/boosts look different on(for instance):
vs
It's the same posts and the same comments, you aren't missing out on anything . However the upvotes, views, and subscribers are all coming from lemmy.world specifically to https://beehaw.org/c/technology
You aren't seeing beehaw's upvotes and number of subscriber, but just because you don't see them doesn't mean they don't exist. This is why I'd urge for people to find one instance to call home. If you make accounts on multiple instances it's just going to cause confusion for no good reason.
I think there have been enough threads created on this but I hope this helps you out.
Worth checking out:
https://github.com/andrewbanchich/shreddit
It also has the ability to wipe your GDPR data for those in the EU.
As @JapanStar49 said, mass edit, don't mass delete. IMO this is just as good as a greasemonkey script at mass editing your history to remove your reddit paper trail.