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Simple Mobile Tools is being sold to a for-profit firm ZipoApps
(programming.dev)
Simple Mobile apps have been very popular among FOSS enthusiasts. I've personally been using the Gallery, Contacts and the Phone app since a few years now. It's a shame that it has come to this, will be on the lookout for their forks.
That's a video transcoder. Simple Gallery could crop videos, trim videos, merge them, add filters, text, music and what not. Good thing it's forked by one of the devs who plans to maintain it.
It allows you to trim videos, but yes, not any other functions you mention.