Big reddit (or facebook) promotion question.

Good day to you BHW gang. I'm about to dip my toes in uncharted territory. I have a service that would be of use to youtubers. Real high value service. So i thought I'd also do some manual outreach to the youtubers for them to find out about me and i offer. I found plenty great Reddit groups, Facebook groups, Discord groups. But i'm not sure what is the most efficient way to reach out to them.

Self promotion is strictly prohibited in most of them so i thought i could use some sort of bot or a VA to send out proposals etc.

That's basically all i came up with. If you have any experience with this i would really appreciate your advice/help.

how would you go about it?