Echo7tango, congrats on the new bike! That's a sweet ride.
Learning to ride on dirt, be it a dirt bike or a
VERY large ADV bike like the GS ( I too have one,) will involve dropping it. Not "if" but when. No one should delude themselves into thinking or let others convince you other wise. Lay your bike down in the garage, and if you can't pick it up, don't even bother attempting to ride it offroad. That's your first training... and if uncomfortable or unable, consider another approach.
I'm a 56 yr old, 5'11" with a short inseam, and out of shape has been rider.

Been riding motos since my age was designated in single digits. I'm not a pro, not the fastest guy, or even most experienced. But I have ridden many different types of bikes and disciplines, on all the surfaces. I only mention this, not put myself out as an expert..... but because I'm probably closer to your age than many.... with the same bike.... a lot of experience... and may relate to you at "our" age.
Riding dirt, even something as simple as a graded gravel road, requires being comfortable loosing grip and or even sliding either of your wheels at various times. Learning to recover, most often means going to down. No way around it, in my humble opinion.

Some one far younger and in better shape than I might be comfortable attempting to learn those skills on a 500+ pound bike. I wouldn't, today, try to learn it on such a bike. Even with my experience, I tender foot my GS on dirt roads. That's just my opinion.
Schedule a day or two preferably with Brian Bartlow at Feel Like a Pro Dirt in Lake County on his small dirt bikes. You can gain those skills on a bike that's easy to pick up with a pro staff, without dangerous consequences. Only a couple of hours from the Bay Area, and beautiful drive/ride to boot.
IMO, better place to start with a higher probability of success and learned faster, than starting training on your bike, even with a pro. It will directly translate to riding your ADV bike. Then consider training on your bike with a pro after... and get more out of it.
Heck, if you bring your GS, I'd even accompany you on my GS around the many gravel forest roads on a midweek ride in Lake County afterwords.
Just my opinion and experience, others will vary. Enjoy the new bike!