I created a little JS tool that is pinging a YT or PT API in order to get the follower counter and display the number on a html page customizable through CSS.
I did it because Peertube lacks an instrument like that which allows you to show the followers number on the OBS scene. With this tool you can just add the html page to OBS. https://codeberg.org/franzbonanza/obsFollowerCounter
Code is FOSS! I hope PT adds my tool to the docs :)