Yes, there are lots of alternate plucking exercises and rake - alternate - rake alternate style finger exercises that I have done from Low End University.
I would have to go watch them again and see if there is a way I can explain it easily.
Or you can go to the Technique section in Low End University and watch LOTS of great exercises for both hands. But it cost $19.99 for per month for an all access pass. You can start and stop the subscription at will, keeping the same account and all.
But I will look up a couple for you and try to post. I think I can download the exercise pdf, so I may be able to post it here.
Yeah, when I played for about 8 hours a day for about 3 days in a row about 2 months ago, my hand and thumb were dead. I couldn’t stop playing tho, I did play thru some pain, but mostly, in order for the pain to subside, I started playing WITHOUT my thumb. It is amazing how much you CAN do with out using your thumb on the back of your neck.
All in all, my time playing like this, has changed the way I use my fretting hand entirely. So much so that I don’t use it sometimes in my normal playing. I no longer have an iron grip and now have a very light, loose grip and fret much lighter, and my Tone is all the better for it.