I wouldn't be surprised if Google is keeping certain performance enhancements closed source so they can have a competive advantage over the competition that uses the Chromium source. They have been slowly making Android open source worse by not updating parts and moving things to closed source Google Play apps.

MP3Gain, the latest stable version was released in 2005 and I've been using it since then. It adjusts the volume level of MP3s using ReplayGain so that you don't have to change the volume between tracks. There may be newer software out there that does the same thing, but MP3Gain is free/open source and it works fine for my needs. I still maintain a library of MP3s, partly because my car is too old to do Carplay/Android Auto, but it can play MP3s from a USB drive.

There is also an open source version you can get on Github for android https://github.com/fexed/Pinball-on-Android

For android I was using Jerboa but switched to Liftoff and am liking it so far.

Galaxy S10e. I love the small size of it and the fact that it still has a microSD slot and headphone jack. Its starting to show its age when it comes to battery life and the USB C port not working as good.

I like the Samsung android software with the customization that you get with Good Lock so I will probably stick with Samsung flagship for my next phone. The biggest thing I dislike with Samsung is the amount of bloatware they ship, the out of box experience is terrible and I usually have to spend a day researching what apps to disable with adb to get the phone usable. I will probably upgrade to an S23 next year. I usually buy my phones used when the model has been out for about a year. At a year old its still new enough to have plenty of support left, but its no longer the current model so it sells for less. Its a better value IMO then buying a new mid range phone, especially as there isn't as much advancement year to year in hardware these days. A year old flagship will have better cameras than a new mid range phone typically.