Awww, ((hugs)) that sounds rough
(Nice to see you btw!)
With DS1 do you think there could be anything else waking him at 5am except the need to pee? I've often wondered with mine whether it is really the need to pee that wakes them, or if it is more that they wake, then think they may as well go? I'm sure you've thought about all the obvious things but just in case - light? temperature? other sounds? Do you think if he's had quite a few early mornings that he could be a bit OT and need one or two early nights to sort things out? How do you respond when he comes to get you after peeing? Is he taken straight back to bed? (Just thinking if there could be any 'reward' from the interaction that keeps him doing it if that makes sense?)
I guess I would be inclined to be quite strict with the gro clock and perhaps consider some sort of reward for staying in his room until morning - sticker chart, marbles in a jar? Know that people have mixed feelings on rewards but sometimes it can be a useful means to an end when the whole family are struggling...
The other option would be to push DS1s bedtime later, accept the shorter nights for now (though 8pm-6/7am wouldn't be bad), and then that would maybe make the morning a bit nicer? I also wonder whether he could be in a bit of a developmental spell of waking early? If that's the case you could always go later bedtime until he starts wanting to sleep in later in the mornings again, then gradually bring it back? It can also be a good way to 'shock' their bodies out of a routine EW - push BT later by 1-2h and hold it until they stop waking at 5am, then slowly bring BT back to a reasonable hour.
It might also be worth considering a later BT for DS2....just thinking that 10.5-11h night is really quite reasonable for a 2yo who is still napping, I only get more than that with DS (2y9m) on days he doesn't nap.
Sorry no magic plan there but maybe something might help?
