Hugs, and deep breaths - it will come right in the end

Nap transitions are always tough and some OT is inevitable. Often whatever you do at these times will be 'wrong' and you will end up with some messy days. All you can really do is EBT as much as possible (if LO is good at making up sleep that way), and push on forwards to the other side. Refusing a nap when you've always had a good napper is very unnerving, I totally agree - but if it makes you feel better it is very normal and common in transition. The logic behind pushing forwards even if he is OT is that if he's going to refuse the afternoon nap anyway, you're better getting the one nap closer to the middle of the day so that's it's not so long a stretch to bedtime. You also have better chance of resettling a short nap if the first A time is longer. The alternative I guess is that you keep your 10am nap but wake him after 45/30/20 mins, and hope that means he doesn't refuse a second one. Ideally you have a pretty short second A time after the first nap to prevent OT.....could be a bit tricky and also quite miserable given how early he is waking though

I think at some point in the past I did see someone here doing something like:
WU 5.30
Nap 10-10.30
Distraction and food galore!
Nap 12.30-2/2.30
BT 6.30/7ish
But I suspect that middle bit of the day would be really rough

We did something a bit similar with the 2-1 when DS was early waking but basically just went for an 11.30/45am set nap, with a quick 15-20 min catnap around 9/9.30 if he needed (basically just made sure were were out and about in car/pushchair at that time so he could doze if he wanted to). That worked ok, maybe you could try it?
I guess just from the outside I'm thinking it's not like he's a 12 month old (or earlier!) and likely to really struggle with just going for it. My feeling would be get that nap to 11/11.30 within the next 2-3 weeks and go for early bedtime, and you may well be all done and dusted sooner rather than later x