The API is still fully functional for moderator accounts, including NSFW posts if you’re moderating an NSFW subreddit. So, you can create a subreddit, mark it as NSFW, set it to private if you wish, and have a fully functioning Boost app again. This trick probably won’t work forever, but enjoy it while it lasts.
Liftoff. I tried Jerboa, Connect and Liftoff and bounced between Connect and Liftoff for a while, but I mostly gravitated towards Liftoff. It’s OK for now, but I don’t think any of these apps will stay on my phone once Boost is released.