My work on fedeproxy started in the same way, i.e. me volunteering. And for @pilou as well. This is very significant funding, at least two order of magnitude more than the hosting costs 
It is reflected in the expense/incoming spreadsheet as a donation to the project
I suggest spending time on User Research. For me it is both brutal and necessary. Brutal because it forced me to focus on what other people need instead of in my own personal interest. Necessary because I ultimately want to publish software hat is useful to other people and not just me.