Game in the Brain

Highly recommend Librera of F-droid

1. Markup – I will be recommending it as I de-google our company and others. You can use it to sign documents.
2. It has Book marking – unlike Firefox and other free PDF readers.
3. Its fully featured – at least the more than bare-bones.

When using F-droid for the first time – there is a I defaults in Chinese , just in the upper right there is language settings.

https://f-droid.org/packages/com.foobnix.pro.pdf.reader