Does anyone know of a way to do live splits on a PS4, either directly (which I assume is probably not possible) or if I'm streaming to Twitch from my PS4?

is there any other way?

is it for streaming purposes or recording for a run to have the splits up?

the only way to currently get splits on a ps4 stream without a capture card is to use Remote Play which will allow you to play the games on your ps4 on your computer.

However it is very buggy and known to crash, sometimes frequently, so it is not recommended as a long term solution or for longer games. Your best bet is to invest in a capture card.