So, I used @pruvisto 's Debirdify to get the Mastodon addresses of everyone I follow on Twitter.

Then, I downloaded those addresses as a CSV, which seems to be in a format used for interchanging AP addresses in Mastodon instances.

Then, I went to Preferences -> Import and Export -> Import, selected "Import Type" to be "Following list", chose the CSV file I'd downloaded from Debirdify as "Data", selected "Merge", then the "Upload" button.

It worked well! ~14% of my Twitter follows imported.

I forgot the link! https://pruvisto.org/debirdify/

Thanks @pruvisto for such a nice tool.

Debirdify

This is a web app that helps you find out which of the people you follow on Twitter are on Mastodon/in the Fediverse already and follow all of them easily.

@evan @pruvisto i have done the thing and manually updated the people! Yay, thank you!
@evan @pruvisto such a nice tool - no fuss no muss
@evan @pruvisto I have to second this. Great tool, thank you!