He said, that Signal server did not get a source code update since 2020. He was wrong. It did, this year February.
IIRC no, it was only updated recently. Git commits are shown chronologically according to their commit date, not their push date. So they could have committed back in February but only pushed recently.
Haven’t tried it yet myself, but I’ve heard that Organic Maps is much smoother and faster alternative to OsmAnd~.