A time at 2.5 hours and he actually gave me a 1 hour nap both Sunday wnd Monday morning
Brilliant! So I would leave it a couple more days and focus on the other naps. This one though, if the nap doesn't go longer after 2 or 3 more days maybe increase another 5 - 10 mins. You don't want to over do it too fast but being overly cautious doesn't help either. At worst he gets OT and wakes up screaming at 10 or 20 mins and has to be re-settled.
And then he did a 40min nap, woke up crying, amd was easy to settle for another one hour nap.
This sounds UT. So he is tired enough to settle for the nap initially but then not tired enough to transition, when he wakes he still feels tired and cries. Depending what A time you did before this I would look to increase again. Be ready at the 40 mins, maybe pop in a few mins before to see him through that transition so that he doesn't wake up too much if possible. We need to gauge whether it's the A time or whether it's ST needed here to teach him to stay asleep.
Do you remember the A time you used for your LO's short naps?
Our routine was unconventional. DS had silent reflux and it was around this time I was getting him started on meds plus fighting the 40 mins naps, plus we had an unavoidable appointment twice per week which meant car naps for 40 mins were all I could offer after the first nap of the day. It really wasn't ideal. The thing at this age is that the A time feels like quite a jump and it increases quite quickly up to 6 months (going to 3hrs or more), the sleepy baby days are over and baby is so much more alert and ready to DO stuff (gaze at you, roll, hold toys) so although no one wants an OT baby you also don't want to be playing catch up for another 2 months with an A time that's too short.
Keep sight of the successes though. And may I also suggest you plan to take a minimum of 30 mins to yourself during the first nap. Go and lay down in a dark room and breath deeply. it can help soooooo much, the laundry and dishes will wait, they really will. Or get yourself to the back/front door and get some air, look at the tress if you have any, the sky...getting some air and light is so energizing after being stuck in a dark room shush/patting.
Keep going