Yes, that is a weakness with many FOSS projects. Developers with great ideas lacking business acumen.
That said, I expect that they can become financially self-sustaining from selling proprietary apps if they can get enough scale. I wouldn’t mind making a small monthly donation long-term but it needs to be less than what they are currently asking.
Some relevant comments from the developer on another forum from about a year ago, when they only had 10 apps:
So apparently it’s been a deliberate choice so far.
My understanding is that the whole point to trying to hire a full time developer is to be able to finally scale their services.