Advice for tackling nighttime potty training?

C

My son has been daytime potty trained for over 6 months now and we’ve been using pull ups at night. Last month he went the whole month waking with dry pull ups/waking in the middle of the night to let us know he needed to go potty.

So I thought he was ready to go without them. He was okay for a week in just underwear but the following week he had 3 nighttime accidents. He’s been wearing the pull ups again for about 2 weeks and it’s the same as before, waking up dry or waking us up to go potty. Which tells me his body knows how to wake up when he’s wearing them but if he’s just wearing underwear he doesn’t wake up.

Does anyone have any suggestions, tips/tricks?