@Prof_Thunder I saw you’d said on my intro post that you were thinking about starting bass.
In case you are still wondering about which teacher, I use James Eager of Ebassguitar. Or maybe you will find him marketing as The Bass Lab Plus. He and Justin follow similar styles in that each video is short (5 - 15 mins) and the content is curated as a learning pathway. Check him out on YouTube and decide if you like his style or not. I’ve only seen SBL and Josh on YouTube, so can see the same as you see. James has a community, but my 1st impression is that Justin’s is somewhat more active.
I agree with the others along the lines of multiple instruments improve musicality in all instrument.
Another pro I would add, is that you can start playing bass in a band pretty quickly. E, A and D open strings, you know where C, G and F are from your guitar. Learn to groove on the root notes and you are good to go. I played in a band 6 weeks after picking up the instrument for the 1st time (really just applying piano note knowledge and knowing what the open strings were on a guitar). Getting good at it is a different proposition, but that doesn’t take away from the fact that you can get on really quickly from the start.
If you want anything more, please ask and I’ll help if I can.
Good luck with whatever you decide,
Simon