Thanks for your help! I appreciate in helping someone with the ring of finishing shame around their neck.
So I took the enclosure, and I just air blew it (with an air compressor) but didn't wipe it down with anything damp. I didn't think to do that, but I'm not sure if that's where I'm getting stuck.
I'm using these fine sanding sponges ( shorturl.at/kxGLP ) since it seemed like the grits matched with what the Youtube video experts were using and it seemed easier to clean than sandpaper itself. I am using everything dry. I first started off with a 60 grit sponge and sanded with the grain. I used my air compressor to blow off the dust, and then I took it outside, but not in the direct sunlight, and applied the first coat of the Helmsman-in-a-spraycan. After about 60-90 minutes of drying, I went and sanded it with a 80, and repeated this process again and again until I was down to 180. I left a little of the varnish on like one video had said to do but overall gave it enough for the next coat to adhere to, or so they said to do. I was trying to replicate the process they were using - albeit they had equipment and I was doing it by hand. Also, it's hard to tell from a video how nice and smooth something really is, but it looked really nice and smooth.
Between each coat I'd use the air compressor to blow off any dust, and I followed it up with a shop vac as a backup.
Being that it was easy to obtain, here's the exact plywood I'm using: shorturl.at/dfrGN and the spray is this one: shorturl.at/hEGQ9 ).
My goal is to have it looked quite finished looking, and very, very smooth. I'm really perplexed as to why it still feels gritty though. The color and gloss seem ok, but the feel of it is so amateurish (well, I am an amateur, but I'm trying to win the adoration of my family by making something that doesn't catch fire and is nice to look at. It'd be a first for me..)