I feel for you. We recently had to take all “screens” (including his phone) away from our son because they were becoming a primary interest to the point of withdrawing from us and the rest of life.
Making this decision was tough because as you mentioned, it is an outlet for him. However in our case he was even letting his grades fall and other life interests drop off, looking forward to only going on a screen when getting home from school. We did frame it to him as this is not a punishment, we just want him to get back to figuring out what he likes to do offline.
We are going to re-evaluate which privileges he gets as his grades and outlook on life (outside of screens) improve. When he does get his phone back, I am looking at two apps to download that will help manage screentime.
Good luck to you!