none of them. mastodon is not innovative from a UX or business model perspective, it's an explicitly derivative product meant to be like Twitter. there is already a Twitter and it is already not much of a threat to other social networks.
the innovations in mastodon are how the network is administrated and (arguably) the differences in culture that network federation creates as an alternative to a centralized platform. those innovations can't be copied or bought by a company already committed to centralized administration, which is almost certainly a compulsory thing for a for-profit business.
This is good to hear--I'd like to know more about how network federations scale when they approach things like critical mass. I hope they have mechanisms in place to safeguard against influence from centralized platforms.
the innovations in mastodon are how the network is administrated and (arguably) the differences in culture that network federation creates as an alternative to a centralized platform. those innovations can't be copied or bought by a company already committed to centralized administration, which is almost certainly a compulsory thing for a for-profit business.