I previously made a thread here about alternative front-ends for Android and Squawker was among the ones I listed. It is an open-source Twitter front-end for Android, but sadly it stopped working that day because of the usual Elon changes to the website.
Today it just got an update on F-Droid and it works again!
I don’t use either, but aren’t there Twitter to Mastodon bridges that will sync posts. Surely if Nitter can get around the API restrictions, the bridges can too.