Well, considering all the current Jolla store limitations, I would advise Sailfish OS application developers:
Don't care about the Harbor limitations and make your application as awesome as possible instead!

I understand the while the limitations are there (apps not breaking due to upgrade, missing API versioning, fear of increased power consumption, missing security mechanisms, etc.) but at the same time they pretty much limit any non trivial application that actually does something useful from being included in the Jolla store.

The best way to improve the current situation is in my opinion to just build awesome applications that make use of the "banned" functionality and publish them on OpenRepos (or any other suitable place of your liking). As OpenRepos has detailed application download statistics this will clearly show how popular your app is and how many users the Jolla store is missing.

This could be a good incentive to either make Jolla to reconsider the limitations (or fix the shortcomings that require them) or might even make OpenRepos the one true Sailfish OS application repository (some might feel that this has already happened) in place of the Jolla store, thus also solving the issue.

Shouldn't just putting rpm on the web and making it "clickable" from the Jolla browser be enough?
Why do we need OpenRepos?

OpenRepos just because awesome Warehouse client and update package notifications

Makes sense. :-)

But still I would advice newcomers, that when it comes to distribution, they could throw an rpm anywhere on the web. Just make that damn app.
I've seen having to understand stuff like OBS, repos etc. to discourage new devs as too complicated.
After a few releases, they will grow into OpenRepos.

I thought the original suggestion was an irony

There are dozens of reasons why this approach is wrong. It's the Windows' "search for an .exe and pray it's not infected way"... I'd rather have newcomers unable to install any apps at all than having them trust random rpm's all over the internet.

The bad thing is, OpenRepos are currently broken (and don't get me wrong, I do use them) as they have no source verification, but psychologically act as an authority (so in the end it is worse, since people are in fact downloading random .rpm's from the internet, but do no feel like they do). Let's hope this changes once they are connected to OBS (plus there's chum!).



Back to the topic, I've looked into timedclient-qt5 and it should be quite easy to create a GUI like Alarmed on Maemo 5 to schedule background jobs. Timedclient-qt5 even seems more powerful than Alarmed, but unfortunately lacks proper documentation.