Question: is this repository still maintained?

[AndroidDeveloperLB]

It seems it hasn't gotten new updates for some time.

Does it support relatively new file types?

For example AVIF, WEBP, JXL, HEIC, APNG , HEIF...

[j256]

I'm not actively keeping it up to date on all file types. If you submit small samples I can add them to the support file.

[AndroidDeveloperLB]

Is there perhaps a list of all supported file types of the library?

[j256]

The list depends on the magic file. You can take a look at the magic file to figure out what is supported. See: https://github.com/j256/simplemagic/blob/master/src/test/resources/magic

[AndroidDeveloperLB]

Cool!