The Memmy TestFlight is full at the moment, but should be on the App Store soon. I highly recommend it.
Mlem and wefwef started good, but imo, they’re not there yet. They both look good, but are still missing a lot of my preferred functionality. Development also seems slow compared to Memmy too, but Memmy’s dev is also a machine pumping out updates every day.
They make very nice audio mixers.