How to get 12 week old to nap longer?

My baby’s daytime naps are less than 30 minutes unless he is in the wrap or in the car. The days I can wear him for hours or we’re in the car for a while are great. He’s well rested and happy. The days where we can’t though.. phew! He’s an overtired, grumpy mess.

I know that it is common for young babies not to be able to link sleep cycles. However, I would love advice on how to help him start doing this so he can nap longer when I can’t wear him or drive him.

(For reference on our nap routine, we do blackout shades, white noise, soft lullaby, pre heat bassinet with heating pad, and use a vibration attachment on the mattress).