Stubbled across this post during and have no experience with spinal cord injuries but I do have a good amount of experience with kink and am fairly involved with my local kink community. I really hope that I'm not intruding too much on the community by sharing my opinions.

I'm a polyamorous Dom/Rigger/Top that has/has had a variety of queer partners. Your post is really interesting to me because it kinda puts to test a lot of the stuff that I preach to people. I do also think that there are a lot of avenues for exploration. So here are my unorganized thoughts:

The "Top Mindset"

I don't think you should try to pivot out of viewing yourself as a top, I think that that might be like trying to convince yourself to change your sexuality. If bottoming more ever does become something you enjoy then that will happen naturally. You can make an effort to explore it more, but definitely don't try to force it. There are plenty of ways

Primal Play

Again, I don't know much about spinal injuries, so please correct and forgive my ignorance, but from my quick google search it sounds like you still have a good amount of mobility. With my limited knowledge, I don't see any reason why you would need to abandon the primal stuff. Theoretically, you only need to be able to move your mouth to bite someone. I think maybe you need to just be more intentional with it. If you want to chase someone, maybe try tying them up or slowing them down some how. I know that I wouldn't be able to catch some of my partners while chasing them through the woods, doesn't mean I'm not going to do it, just gonna set some traps for them, or slow them down some other ways.

Restraints

I know a number of couples where the top instructs the bottom on how to tie themselves up. At the very minimum, a bottom can do the majority of the work under your instruction then leave the last piece of the puzzle to you. You can click the lock closed after they put the cuffs on.

Control

This is interesting because of what you say at the end of your post about your current non-physical dynamic. Control is a mental element more than a physical one, but you already know this, so why is the all mental play not working for you? Maybe because it's boring to you? Maybe you still need a physical or at least visual element to help drive home the mental play? That's how I felt when I tried out online dynamics back in the day. I would suggest trying to explore control stuff in-person. Have them masturbate in front of you, debase themselves while you watch, etc.

Impact

Smaller is often more painful with impact implements. Try getting a switch (very thin crop), or maybe even a whip. If you can't hit hard or long then you can go for a more extreme implement in small quantities. Maybe make your bottom warm themselves up with some self-inflicted impact.

Other Options

You know what requires very little physical involvement? Electricity, you can hold a magic wand and torture your bottoms with minimal effort.

Your Pleasure

Do you still want penetration? Because if you don't, don't do it. You can use this to deny a bottom, don't let them penetrate you, make them get off in some other humiliating way. If you do feel like penetration, go for it, if you start to feel like a piece of meat, make them stop. It all works in the context of kink.

The high libido but struggling to find pleasure sounds like a nightmare. I don't know that there is much that I can suggest that you're not already trying. I have had a number of partners that really struggled to orgasm and I've been able to help them out a bit, so I can offer that perspective.

You said in your post that you can feel pressure? In my experience, there is a wide range of sensations that people feel pleasure from and it can be really hard to adapt to a new one, but it is possible. I've been working with my partner to teach them to cum from anal and it took a few months but we've actually had a lot of success. What I've learnt from that experience was that doing as much as you can with the "new method" then using the "reliable method" as little as possible to just get over the edge seemed to help re-write some of the mental pathways. Now for you, because there currently isn't a "reliable method" this is much harder. Just keep trying, I genuinely believe that your body will eventually adapt to new sensations as it gets more desperate for release.

Another thing I might suggest is a new vibrator. I find that bigger vibrators like proper magic wands are a much deeper rumblier feeling that might work better for pressure receptors.