I am Suzielli Mendonça, a Xodo user since its beginning and a beta tester.
First of all, I wanted to congratulate the Xodo team. The app has undergone several improvements, and it is one of the best I have ever used so far.
I am not sure if you are looking for new ideias of improvements and resources, but here is one: for mobile users, it would be great if the post it feature (in portuguese, it is called "nota adesiva" - the picture of it can be seen in the image attached) could support handwritten notes. Xodo would be the first app to have this feature.
Thank you for your time,