"the only reason I'm still on Reddit is that there aren't any alternatives"

To add to your point, I only found out about the fediverse because a couple of the subreddits I was active in made a post declaring that they were going to move (or at least start up another version of itself) in the fediverse. I'm currently still on Reddit because I'm not seeing enough content, and the federation seems really hit and miss, to serve as a sufficient alternative.

Until you've got a critical mass here, I think it'll be necessary to use reddit itself to help raise awareness

Honestly, I haven't noticed a difference on reddit yet, community and content wise. I've been dipping my toe into migrating as I've seen two of the subreddits I'm part of setup on alternate fediverse instances (lemm.ee and sffa). So far, it's been rather disappointing though.

The federation hasn't seemed to work well on either platform, so this is the third account I've had to make in order to participate in a discussion.

I use straight up reddit on my desktop computer, I don't access it from my phone except in extremely rare circumstances, so the changes for third party apps don't really affect me. Part of me wants to show solidarity, but if I'm not going to get a remotely comparable experience, then I don't really have an incentive to quit Reddit. Many of the subreddits I'm interested in haven't made any migration that I'm aware of, and I didn't see substitutions for them in SFFA