I was wondering if there were any world viewer (Apps that let you look at your world's and show were different biomes are.) apps for mcpe that work on andriod. I know about Blocktopograph but it hasn't been updated and doesn't work with the new update.
YES! I know of a really cool one called papyrus! It was designed to work on servers and has a utility for making backups, but if you point it at a db folder it will render everything into a Google Maps style index.html file!
https://github.com/mjungnickel18/papyruscs/releases
This is the link to the code ^^
https://github.com/clarkx86/papyrus-gui
This is a link to the GUI, way easier to use and switch the different options like elevation layer and if you want an underground or aquatic map
they also have a map of their survival server, so you can see what it do [ http://papyrus.gwsa.de/ ]
I can help with troubleshooting if you run into any issues, but they also have a Discord server I recommend joining.