You may be able to use a back door through brand management and add an account manager to the youtube account, thus changing the email on file. I don’t fully understand it and I don’t even personally have a youtube account, but it’s done through google services as I remembered podcastage talking about it.
Long story short, he lost access to his large account over a suspension of his small personal account and the two were somehow linked. This is him on another of his secondary channels mostly whining about the situation as a whole, I tried to timestamp the relevant portion of the video but the resolution is presented amidst a lot of complaining so you’ll have to determine whether or not this is useful to you.
Also, I don’t know which google services you still have access to but at least it’s an angle you can investigate and it may be contingent on whether or not your channel is monetized, that part I cannot say.
