Supporting Lemmy won't do much to help the Threadiverse thrive imho. Instead I suggest supporting PieFed, for many uh... reasons. One being that it is written in Python (which many developers are already familiar with, rather than the extremely niche Rust that even experienced C++ coders are loathe to have to learn) and thus has a ton of features already that Lemmy lacks (see https://join.piefed.social/features/), plus it's only continuing to add still yet more, on a monthly basis even.
By comparison, Lemmy requests sit for literally years and years, while a lot of the donations, rather than going to support further code development, instead goes to support the, let's just say "highly controversial" instance lemmy.ml.
Lemmy won't "die", but it's never going to hit mainstream. Visit r/RedditAlternatives in any given post to find out why (hint: tankies, which Westerners do not like, probably bc tankie instances are full of content calling for the literal murder of Westerners as well as the actual fall of those civilizations - for some reason though these anti-Western sentiments seems to drive people who live there away? Go figure!π€ͺπ).
PieFed on the other hand might just have a chance, and the dev team is super friendly and highly responsive. At least check it out.
Also, post content! More than most other things you could do, that would help a lot.