The Phillies might be done this offseason unless something falls in their laps
Going back to the start here, the Phillies don't have a lot they absolutely HAVE to do the rest of the offseason. Re-signing Aaron Nola was the biggest thing they needed to accomplish and now that that is done, everything else is just gravy. Sure, they are going to throw their hat in the ring on Yamamoto because this is Dave Dombrowski we are talking about after all, but the Phillies don't seem to love the rest of this free agent class.
Adding a bullpen arm or two would be nice, but there has been little in the way of reliable chatter connecting Philadelphia to the top relief arms like Josh Hader or Hector Neris who are going to be asking for big money. It seems more likely that they sign a quality 7th-inning guy more than deviating from their flexible bullpen strategy and signing a dedicated high-leverage guy.
The Phillies clearly are open to upgrading their rotation, but getting much better than what they have isn't going to be easy or cheap. If they miss out on Yamamoto (which is probably the safe bet), they are rumored to not be in love with the idea of Blake Snell and there has been no connection to Jordan Montgomery's free agency beyond idle speculation.
In short, the Phillies may be done this offseason for the most part and that is okay. Now if only they can get an extension with Zack Wheeler done so that he doesn't hit free agency after next season.