2 to 1 nap transition / nap training

Our almost 12 month old has been waking early (4:30am) so we are thinking it might be time to transition to 1 nap. He was sleep trained at 4.5 months and used to sleep 10.5-11 hours pretty consistently but in the past month or so night sleep has been anywhere between 9.45-11hrs. He will also not settle independently for naps anymore. We didn’t nap train previously as he was just able to do it post bedtime sleep training. Now we are having to rock and hold for all naps. He still settles independently at bedtime.

How can we transition to one nap when he wakes as early as 4:30am without a really early bedtime?

Any tips on how to nap train would also be appreciated. Whilst he used to be able to settle himself, he has never been a long napper (rarely more than 1.20/1.5hrs). We cap total day sleep at 2 hours and have for months.

His wake windows are all over the place but we try for 11-11.25 hours of awake time - although it doesn’t seem to make a difference to whether he does a 9.45 hr or 11 hr night. We don’t really know when he’s tired. He’ll yawn an hour after waking up and then be full of energy and not show any sleepy cues. We’re at a bit of a loss so appreciate any guidance! Thanks