RetroRgb- great retro content in general, his weekly round ups and questions are incredibly useful. He also has a discord for patreon supporters which has a pretty chill group.
Voultar His videos are the best soldering tutorials on YouTube for consoles. Also his snes and N64 RGB mods are super simple to install for beginners. His video on the N64Digital really helped me install my own.
Macho Nacho He does pretty good coverage of newer mods and explains the features in pretty simple terms.
My Life In Gaming These guys have to be most in depth and unbiased reviewers of retro hardware.
Console Mods Wiki a pretty good site that covers a lot of information on retro consoles, still a work in progress
Console Repair Community this one is not too active (I’m most of the posts) but hopefully we can get more questions there.
And finally any of the individual communities on Lemmy for individual consoles. They aren’t the most active but if you post questions hopefully there are people to help answer (I subscribe to many of them and try to help when I can). The important thing is to ask detailed questions and provide pictures when it would help.