i want to contribute to .ml and minimize how much of my effort goes to .world or .shitjustworks; i think my IT experience would be more beneficial to this end.
As others mentioned, you can either donate code or money. If you want to help Lemmy.ml the most, I recommend the Patreon linked above since it goes straight to the Lemmy.ml admin (who very much needs cash to stay afloat because he's been working on Lemmy full-time for years, for peanuts)
lemmy.ml runs on the vanilla Lemmy codebase, so from a software development standpoint, you mostly can’t pick & choose which instances you’re helping. You can work on whichever features/GitHub tickets you’d like to see on lemmy.ml (though keep in mind that a few features are optional/configurable, and the lemmy.ml admins and/or user base might not want some enabled. It’s a good idea to read the room before investing the effort).
no reddit diaspora sites has ever survived and no instance on the lemmyverse has the critical mass of users necessary to recreate reddit's subreddit communities.
the people looking for a reddit alternative will leave and .world will become like any other instance after .worlders start to miss the niche content enough.
As for this valid focus on critical mass of users, perhaps a linked tags approach is better than a multiple-communities structure, until specific tags gain enough friction to become communities. Just thinking.