It looks like this is a bit quiet on the waveform, however going to turn it up for the sake of review. I think where this shines is actually in your percussion. It is quite dynamic for such a limited range of frequency. I think something could be done to get a bit more punch out of the kick, perhaps find a frequency that doesn't clip out so much at the bit rate.
As far as melody, the portamento shines atop the almost lackadaisical up and down arrangement. I think the supporting countermelody can get a bit busy, particularly at 12 and the repeated section -- largely because we already have fast moving hopscotch percussion and the melody is quite slow.
I would like to hear more of the bass on this piece, if you have the possibility to turn that up in I assume beepbox. I'm not very familiar with this tool. I also think that you could maintain this internal loop and change the break before 18-20 seconds leading into the new section. It sounds better as a true finale stinger before the swooshy transition, as opposed to leading into a B section. I hope I am able to make this clear.
What I typically do when I am making a short drop like this is start with 4 bars, copy. Change bar 4 and leave bar 8 as the final fill. To extend to 16, I do the same process, change bar 4, 8, 12, or 16 accordingly to keep the illusion I did NOT just copy and paste everything. And I generally make changes in the bass or the harmony instruments before I touch the lead. It keeps things fresh.
There is another principle to building a song structure -- add 2 things at a transition, then remove 2 things. Keeps things dynamic. Can be done with one element at a time of course, but it helps keep things shifting ever so slightly, and is a great exercise in creativity. You are already doing this to some degree in your guitar knots pieces, I see.
Again, great to hear from you, and happy to see you improving each time!