Seems hard to play and sing at the same time
I think the key is, as soon as you can play a song, start trying to sing at the same time. That worked for me on guitar without much difficulty. Now I'm going back and trying to learn to sing and play bass at the same time (by best instrument) and it's taking some work, especially on parts of songs where the rhythm of the vocal part and the bass line don't match up. I also like to improvise a good amount on the bass, which is making it more tricky to put together.