My idealistic answer would be "go back to the drawing board to create a business is not built on someone else's land."
Do you mean advertising or keeping an internet presence? If you mean "internet presence", I'd would use one of the numerous site builders and I would create a pixelfed and mastodon instances to publish content.
If you mean advertising: I'd write a post here about how my account was banned without justification...
None of these options let you change the status quo. It's like arguing about tipping. Whether you like it or not it exists and the social norm doesn't change because of your individual decisions.
You just need to stop contributing to it if you believe that it is harmful to you and you are okay with the consequences of your choices.
I am not walking around with a soapbox telling everyone they should leave FB and Instagram. Instead, I am simply not participating in it and hoping that this can serve as an example for others.
Ok, your small online store is banned from advertising on Facebook and Instagram. What will you do?