There basically aren't any. Almost any entity that would want to buy the company should by definition not be allowed to do so.

The ideal solution would be for all data to be deleted before a sale. If anyone would want to buy 23andMe without the collected data then that's perfectly fine.

My ideal would be customers given the option to have it delete sold and profit split with between themselves and 23&me, or anonymised and donated to the human genome project.