Likely a controversial take:

Does this flash flood of new users make Mastodon/Fediverse bigger?

Hell yes!

Does it make content more interesting and varied?

Certainly does.

But does >>a million twitter emigrants make this a /better/ place?

No, unless you like having your door kicked down and a flock of colonisers fill in your living room, telling you how to run your social sphere/instance/federation with long-winded speech codes, omnipresent Content Warnings, and the whole nine yards... 🙄