@highvizghilliesuit @atomicpoet @LouisIngenthron it's entirely possible to use different software and add features, just on mastodon there's hometown and glitch-soc forks that add features (some I really like and miss). There's also many other apps like calckey and friendica that have entirely different feature sets. However, if Microsoft were to make a fork of mastodon, they have to make it Open source and I believe also gpl compliant.
@highvizghilliesuit @atomicpoet @LouisIngenthron however, if they're activitypub compliant, you'll still see the posts on mastodon and the features you have. There's already @pixelfed that could easily add those filters in the future