It's fairly normal for humans to go into semi-awake stages at night, normally fully waking comes because there is a factor eg a noise or something on the mind. 2yo go through a lot of mental growth & with that, they are understanding relationships better and when they are away from their "primary connection" (usually Mothers) they often choose the night to "demand" that connection that they naturally require.
So in many ways, maybe it's not really about the routine, but his physical need to know that you are there when he needs you.
Also because he needs your hand as he falls asleep, when he gets into a light sleep cycle, his body is programmed to expect the same conditions. So he probably needs you to gradually wean off the hand holding. Swap to a gentle pat, then slowly less pat over time (days not one evening) Then over a week or more if you can get to the point you are just in the room without the touch, you can move your self further from his bedside. When you get to a point that you are near the door you could do timed leaving. Where you literally tell him "Mummy is just ..." & you duck out of sight for a few seconds & return & over time you make it 10 seconds then 20 etc. It's a journey to fix it, many weeks & it may not even solve the night wakes if it's emotional.
I know for us the issues were more related to a sibling being born & shared focus & for my DH & myself we ended up putting a mattress on the floor in his room & camping out there so we could get the sleep we needed. It didn't last for ever, but it got us to a point that we were less exhausted.
