The above projects are open source. So those are definitely areas where you can pitch in!
Re:I will work on one project for free
by subinsebastien on Monday February 19, 2018 @10:22PM
(#16417609)
I have not considered open source projects which are in development, since it prevents me from having an opportunity to develop from scratch, also highly likely that I have to use toolchain which the project is already using, as opposed to tools that I'm familiar with.
LibreOffice has an Android version: https://wiki.documentfoundation.org/Development/BuildingForA...
These are the projects I am affiliated with.