App loader question: does it make sense to post niche use applications

I'd say that any decent app is a nice addition, even if you are the only owner of this particular device, quite possibly someone else might want a similar app, so they could adjust/copy your code instead of starting from scratch.
And it saves you some trouble if something changes which applies to all apps. (like e.g. the recent metadata change)

But it should be a complete app, so you should consider if it's worth the effort of creating a nice icon, README, screenshots, etc. (My watch definitely has some "unofficial" apps because that was too much effort.)