HELP toddler won’t stay in bed

Our 2 year old has done very, very well in his room until the time change and we have been fighting it since. He will not go to sleep until 10. We have a strict bedtime routine. He’s in bed by 8, but will not stay there without a fight- he gets up and out of bed. We’ve done the 100 walks back to bed every night (not a joke). He doesn’t seem to wear out. We’ve put a baby gate at his door and he sits, screams and climbs over it.

I should also mention he is waking up between 1-4 every night and will not fall back asleep unless you let him in your bed or lay with him but he’s back up at 4:30-5.

Any advice would be helpful, I’m 9 months pregnant and already exhausted and want to nip this in the butt before we have a newborn.