Toddler sleep help

My toddler is 20m and a sleep disaster. Historically he was always a good sleeper. I fed to sleep for a long time but it didn’t prevent him from resettling himself. Then I did the “I’ll be back in x minutes” method which worked within a few days. Now we are really struggling and have been for ~6 weeks. Schedule is one nap, ~5.5-6hrs after wake up. It is extremely hard to get him to lie down. He is in a toddler bed due to height. When we go to his room he just runs around. If I can get him to be still (eg we are on out way home in a stroller or car, or I put him in the pack n play in the kitchen while I do dishes - which he is also really too tall for) he will fall asleep usually. But I am about to have baby #2 and this isn’t a great solution. At night, he will not stay in his bed but immediately be at the door sobbing. He has a very sensitive gag reflex and sobbing can make him puke in a matter of minutes. So we lie down with him snuggled on the floor til he falls asleep, then put him in bed. He may or may not sleep through the night, but he is getting 2y molars (and also huge growth spurt and maybe nightmares?) so I am ok comforting him tbh. For 1y molars we had a couple rough weeks then he just magically started sleeping again so maybe it’s wishful thinking on my part.

Anyway any advice is welcome. The nap is my biggest concern tbh. In general with sleep training, the issue is all methods seem to result in immediate crying. Since this causes vomiting, I just can’t do that. Then we spend 20 min cleaning up vomit and changing and calming down and if I just lay down with him I’d probably have him in his bed and me out the door in 30 min anyway (for nighttime; at nap he won’t lay down). Bedtime routine is bath every other day, otherwise straight to pjs, stories in parents bed with a bottle, brush teeth, go to bedroom and honestly at this point just turn out the lights and lie down together. It used to be put him in bed and sing a song and then leave (he’d still be awake). Nap time is go upstairs, take off sweatshirt and put on sleep sack, bottle and a song, and put down. He might fall asleep with rocking or get in bed awake. Now the second you enter the room he turns into maniac bug…