I think you've stumble accross few of the huge issues with selfhosting

- Developing apps is too hard, you have all the difficulties of SaaS development but with the added difficulty of having to support people installing your app in various setups

- For the difficulty, the return on investment is low because the community is much smaller than what you can touch with a SaaS software

This causes the breadth of available apps to be quite shallow, and additionally, another factor threaten further that diversity is that

- people gets into self-hosting in one of two ways. Either to create illegal media-center (in which case they install Plex, Jellyfin, *arr, download client, etc...) or to manage their document in privacy (Nextcloud, etc..) seems like you are type 2. This causes most projects to focus around those hot topics, without exploring other things (this year alone at least 4 photos albums backup software started development..)

But this state of affair is not sad or inflicting, it is natural for such as a young community to take time to find itself, especially in this difficult setting (I know selfhosting is not new, but I call it young because only recently did it start becoming so popular). And there are solutions to those problem too. On my end, like many other talented people, I am working on technologies to improve this situation, and hopefully one day we will see a large diversity of application growing, with much more accessible setup for people to run.

What I forsee will be big in the future

- Once we crack federation (I do not think current state of the technology is good enough) social app (Video sharing, file sharing, social media alternatives, news site etc..) will be big

- Going back to news, once we improve the QOL of SH for public sites, news agglomeration is going to be big as well (for blogs and stuff)

- Any mobile/SaaS app could have a SH counter part, that will automatically gain benefits from not being in the cloud. Im thinking things like various task management, productivity tools, and of course, home automation is gonna be the bigger winner for being in the home already, therefore workable offline. An example of this is already happening with cooking/recpies apps (Mealie, Tandorii, Grocy, etc...) which benefit from being at home, private, and accessible from the family, and home-assistant.

- Finally, SH is going to supercharge the development of very niche software. It makes no sense to develop an entire SaaS offering for 100 users (ex. a software to manage your model train would be very niche) because you have to pay for a domain, servers, and so on... But a SH app could literally cost $0 to run (for the devs) while yelding minimal benefits (either from subs or donation).

Give it 2-3 years for those stuff to develop better. In 3 years this sub will be almost twice as big at 500k, and you will have 2-3 times the amount of apps available that's pretty much a garantee