Trying to save my ad account. Need advice

Experiencing an unforunately all-to-familiar story of FB randomly restricting ad access to my FB page. Have had the page for about 12 yrs, haven't advertised in about 7yrs (no issues at all), wanted to start advertising again and found out my page got restricted about 8 months ago. No idea why, went through customer support (if you can call them that) and no change, they don't know why and can't seem to be able to restore it. I know at this point the page's advertising ability is likely gone and I need to move on.

I've heard that what I can do is try to separate my FB and instagram accounts so they're not linked to see if that works. I believe I've done that but would love some help as to what to do next. How do I advertise with just an instagram account via ads manager? I thought FB page is required. Should I be setting up another FB page just for advertising and connect that to the instagram account? Is it normal to have 2 FB pages because of this? Is there perhaps an alternative route that I haven't explored yet?

This is for an established business that already has thousands and thousands of followers, so Ideally I don't want to abandon that page - same with the instagram account.

Also, I still have FB pages of another business that I had that no longer is in business but the page hasn't been shut down. It seems to still have advertising access. Does it really matter if the source FB page/etc doesn't match the product/brand being advertised (just thinking out loud on this one)?

Any advice would be greatly appreciated. If you have a link to a video, article, or tutorial etc. - that is also welcome. I'm relatively a newbie (from an ad perspective) and a lot has changed since I last used to advertise, so might need a bit of hand holding at the beginning.

Thanks in advance for all your help. I know this is THE spot for all things FB advertising.