I’m a big believer in general strengthening to help with any kind of physical activity (including guitar). When you’re stronger, things are easier, and you’re less likely to get injured.
There is a reason that almost all professional athletes, regardless of the sport, work out in the gym, and work on rehab and prehab exercises. Because they prevent injury and help them perform better.
My personal experience was a long time ago. I spent a lot of time at a drum kit, and also in front of a computer - studying computer science in uni and being a computer geek in general. I was around 18. I ended up with major pains in my wrist - RSI, OOS, carpal tunnel, whatever it’s called this week in your part of the world - even at such a young age. I was scared I would be permanently in pain so I quit drumming and sold my kit. It was the main reason I stopped (that and I needed the money to travel and see a girl… that’s another story). My career was going to be in front of a keyboard. The pain didn’t go away, though.
So I did some research, and started using hand grippers. Things that look like this. Not those exact ones though. I started with a light set, and used them a few times a day, every day. The pain went away. Then I graduated to stronger ones over time.
The pain has never come back.
Eventually I went to the gym and lifted weights. I don’t use the grippers anymore. Lifting weights uses your grip strength, which does the same thing, to a degree. I’ve been inconsistent with gym over the years and as I’ve got older I’ve got a couple more persistent injuries/niggles (caused by working at a computer and some sports stuff, not wrist related). The pain goes away when I go to the gym, but if I don’t go for a couple of weeks, it comes back. Hmm, gotta be something in that…
Having strong grip strength helps with barre chords, or playing for extended durations. No, of course you don’t need to do it. And I don’t believe there would be any “guitar-specific” benefits other than general hand strengthening. But that is probably a good thing in general. I see lots of posts from people with hand pain and fatigue issues and I can’t help but think that some general strength & endurance would help.