Glad you found it useful! I often think if my feedbacks are overly critifal. I just give out same kind of feedback I'd like to receive myself. And of course pointing out what are the aspects that could be improved on is more useful than focusing on what does work. Even if one wouldn't do any post-jam version and fix any issues, it's still a possible learning experience and one might avoid the same mistakes and design flaws the next time.
I found that Godot's GPU particle systems are the biggest framerate killers when you instantiate them for the first time. My game completely froze for a good 10 seconds or so the first time an enemy was killed the first time I tried the web build on PC. Weirdly enough on (a less powerful) Mac it wasn't just a couple of dropped frames and while playing on editor, it was completely unnoticeable.
I feel ya, I'm completely solo too (though this jam I had a colleague of mine do music). It is a lot of work to juggle all the different aspects of development. I usually do 48 hour jams so a full month long jam feels like an eternity 😅 but that too can slip away fast, especially if one has some other priorities like you did this time.
And since you plan on doing a post-jam version, one other thing that would give the game much more replay value and longevity is more powerup variety. I think maybe doubling the current pool would be a good number to aim for. I think that'd be enough that you would get more varied choices and especially the common ones wouldn't always be the same. Dropping one of the pick options to that classic "choose one of three" too might also be worth considering as that'd increase the build variety per run as you couldn't always get what you want. Even super simple additions like basic stat boosts that you already had a bunch of would help the variety a lot. Stuff like damage, reload speed, acceleration (never really wanted to take the speed boost but better acceleration would have been awesome), less knockback or more invunerability frames etc.