I noticed that some of the mods here are also the mods of r/experienceddevs. That subreddit is quite active. Perhaps it would be effective to have automoderator throw a sticky on every post there, just saying welcome to r/ExperiencedDevs, please follow the rules, etc and at the bottom: Did you know we have a Lemmy community? With a link here.
Of course. People that left and came here because of the API stuff are (IMO) inherently smarter people with a predisposition toward FOSS technologies.