Hi @supaiku! Your question is pretty broad, but lets try... Other ways of contributing to apps than writing code:

reading code 😛 - some tasks like creating developer documentation, only needs you to read and understand the code helping with design creating art work like app icons making mock ups for new apps taking administrative burdens from developers by managing issues for example (being the maintainer of an app you know very well is possible without knowing how to code) help testing of course by joing the ubports qa and test telegram group or: more structured tests were nice in some cases, but someone would need to create that (infra)structure, either by creating and managing test tables, which are filled by testers or by setting up more advanced test managing systems (i.e. see http://www.systemtestportal.org/) translating apps maybe you find enough app devs around you to host a hackathon