Unless you expect to interact with celebrities/politicians/comedians/brands, you can follow them just fine from the numerous twitter mirrors.

What's left are your friends, and for those I had a mixed strategy: help them set up accounts on Mastodon and still follow their twitter mirror. The ones that stayed on Mastodon, I can interact directly. The ones that dropped out, I follow their mirror and I ping them on im/email/phone when something they posted is a good hook for a conversation.