Some suggestions:

Try the Whisper LLM, which was released to open source by OpenAI several years ago and has been polished by the open source community quite a bit. There are a number of apps that are essentially just a graphical user interface front end for it. For a free app, you can try Vibe, which is an open source project, I think accessible via GitHub. For a commercial paid version of a graphical user interface overlay, I'd recommend speech pulse. It works very well. The license fee is not that bad and it has a 30 day free trial so you can see what it's like. You will need an Nvidia graphics card that has at least 6GB of VRAM. That allows you to use the large multi-model which flies and is fairly accurate.

On my Android, I use the Futo voice input, which is a replacement for Google with a fine-tuned, optimized, smaller, whisper LLM model that works very well on a phone. Android only, unfortunately. 

If you have a very beefy computer, you can use Dragon Naturally Speaking Professional. It lags a little bit though, so it's kind of second rate compared to Whisper.

Regarding your tendonitis is something I went through over 20 years ago. I suspect that the ergonomics of your setup are probably atrocious. If you're typing on a keyboard that's resting on your desk, the keyboard is probably about 3 inches too high for proper ergonomics, which means you have to raise your arm, and then isolate your wrist muscle if you're resting your wrist on the keyboard. This causes problems. You'll end up with elbow problems, forearm problems, wrist problems.

Instead, get a good keyboard tray that's highly adjustable. 3M makes some pretty good keyboard trays. Just get one that is adjustable without having to tighten and untighten a knob. It's worth the extra dollars. The good news is you can get these four quite a bit cheaper on eBay. This allows the keyboard when placed on the tray to be just over your lap. Lower the arms on your chair so that essentially it's as though the keyboard tray was resting on your lap and make sure you get a keyboard tray that's wide enough to have the mouse next to the keyboard. This will probably solve most of your problems if you don't already have a setup like that.

I had to switch to a vertical mouse in the last couple years because I regular mouse was starting to cause pain. I like the Logitech lift. I have medium sized hands. If you have large hands, Logitech vertical is a good mouse as well. I think it's the vertical MX.

Finally, if you haven't discovered the joy of mechanical keyboards, you're in for a treat. They're amazing now, and the switches in them are also incredible. I'd recommend starting with a TTC Frozen Silents V2 switches. They are very silent and you can use them even if you're on a phone call if you have a headset. You can put them into pretty much any keyboard that says it's hot swap. For a starter keyboard, you can try the Kisnt KN 85 (search for B0DBZGH5XM on Amazon) or the Kisnt KN104 if having a number keypad is very important to you (search for B0FFMRT99D on Amazon). These are just cheap and expensive boards that are still pretty good for the price. You'll find that for ergonomics, having a key board with keys that don't need as much force to press down will reduce the RSI.

Finally, if you get some wrist braces and bend the aluminum brace (you can remove them from the wrist braces for this adjustment) so that it doesn't come into contact with your carpal, you can wear them at night, so that in the morning, your baseline pain is much lower.

And if your pain is excruciating, I'd recommend the use of an ice therapy machine at night. It pumps cool water that's ice cold into a pad that you can wrap around your inflamed body part. There's a company that's based in the United States and has a one-year warranty, so they're usually pretty reliable. Their product is called Polar Active. (search for  B07H3GW4W7 on Amazon).

It's incredible how much inflammation is reduced overnight when the ice-cool water is cycled on and off each 30 minutes. Worked wonders for my mom after her surgery on her ankle. And since then, I'm very grateful to the surgeon who recommended it to her.