Richard, I'm very sorry to hear about your vision troubles. I'm certain that it is a frightening and frustrating experience.
I'm a lefty, so I've had a lifetime of having to adjust to the right-handed world. As some encouragement, I'll say that eventually it becomes natural to shoot "wrong-handed". Shooting glasses with a blind over your dominant eye will help there. Blanking out the dominant eye seems to force the brain to adjust .
I've found that I still test as left eye dominant, but when shooting it doesn't matter now, I don't need to close or cover my dominant eye anymore.
Shooting rifles right handed with a cocked grip to use the left eye causes most people to place their teeth against the comb. This is a very bad idea that can lead to some unanticipated dentist visits. Also you'll likely have your face closer to a scope trying to shoot that way, leading the way for scope bite. So moving over to shooting as a lefty might be your best bet. Try the shooting glasses with a cover over your right eye if needed. Putting the glasses/blinder on a few minutes before shooting helps. I suppose an eye patch will work also if you like the pirate look.

I did meet one vet, blinded in his dominant eye by shrapnel, use an offset mount(used on many CQB rifles for a secondary sight) to continue to shoot right handed while using his left eye. It wasn't a perfect solution for him, but he made it work. He said that couldn't get used to the brass flying in front of his face while shooting ARs left handed. Since he already owned several right handed rifles, he came up with that offset solution. It looked awkward, but it seemed to work with some effort. Instead of canting the rifle away from his face to acquire the sight as most do with these mounts, he just used his good left eye and look through the angled sight with the rifle held in a normal vertical position. Picatinney rails are ubiquitous these days so offset scopes/reflex sights are possible on most rifles, but I'm dubious if I could adjust well to that configuration. You'd have to try it to see, if you wish to go that route.
For pistol shooting with a cross dominant eye most instructors recommend cocking the pistol 10-12 degrees toward that eye. This seems to work very well for everyone I've shown. Now that both of my eyes are used to shooting as dominant, I can cock the pistol and have my right eye "take over" automagically.

Consider the process more like the adjusting a dimmer switch than an on/off switch. It takes a while, but eventually it becomes natural to work with the non-dominant eye and wrong side grip. I do it now without thinking. Your brain will adjust, it's an amazing flexible thing.
Good luck and I wish you all the best.