I would recommend learning the modes as well as how chords are constructed from them! When I say modes, they have names like Lydian, mixolydian, Dorian, etc. they all derive from the standard major and minor scales, but if you start on for example the second note of the minor scale rather than the first, you get an entirely new scale plus new chords and note relationships from them.

The best part is that all modes can be played or based on any note as your root.

IMO it is a very versatile way of both understanding and writing music, and is very light on the “traditional / classical” side of things. It can apply to piano too but it makes way more sense on guitar because all the scales/modes will look the same no matter what key you play them in (unlike piano where you have to take into account sharps and flats)

Without any music theory to fall back on you're really going to set yourself up for some frustration - especially if you aren't willing to study already written music. Ideally you would learn about keys / scales and then recognize them within the music you would like to replicate while learning the piece yourself. I would bet that you're struggling to resolve your own compositions mostly because you haven't studied how whatever style you're trying to replicate solves this eternal problem of writing. It is tough and something that every writer will struggle with.

What I find really isn't helpful. For one, I am not starting with a melody; a ton of this content assumes you are.

Yeah that's because it's a lot easier to do it that way. You can outline an idea, then modify it through modal shifts due to the underlying chords while adding flourishes and whatnot to really fill it out. This isn't possible without at least some basic theory though. Even chord progressions without a lead will often work on the principals of melodic intervals moving within the chords.

Playing with other people is great, but without any music theory it can also be very unproductive. Depends on what style you're going for.

Two, a lot of it just really doesn't discuss the- I guess philosophy and approach? Mechanically i'm already at a point where I can play a song, but I haven't been able to self-discover a process for taking my own material and whipping it into shape, and focusing it up?

For me (and most people I know) the best / only way to do this is by using composition software. Being able to separate your fingers from the idea can really open up your writing in ways you would never reach for while trying to play at the same time. Also really helps to hear it back with the ability to make small changes repeatedly, save different versions for comparison, and even just to shelve an idea for weeks at a time without forgetting it. I've always used guitar pro, but I know there are some free options out there like tux guitar. Personally I'd just pirate guitar pro if you aren't able to justify the cost. It's very good.

I'm not on here too much these days and just got lucky seeing this post, but I'm a former guitar teacher and current full time musician, so happy to help point you in a helpful direction if I can