> "I'll create the software X to fit my own specific requirements/needs, then I'll see if anybody else wants to use it as well (which would mean that that niche of people have the same needs/requirements), and if that's the case then I can decide if to put more energe/effort/$ into it otherwise it will just be something useful for myself" > > ..., right?
At a high level, yes.
(At a lower level, well, there will be variations on the same basic idea. The devil is in the detail.)
> I think that for that to work the important detail about the concept&implementation is that the SW must be complete > ... > and that the full functionality will be always available, even if in the worst case I don't have an Internet-connection.
Yes, GigoBooks is intended to be desktop linux/mac/windows software that runs entirely offline. If the OS doesn't change, it can keep operating forever.
> Btw., the GigoBooks app does not currently allow to save data, or did I overlook some menu-entry?
You're looking at the online demo which is necessarily functionality-limited because web browsers don't allow access to local files.
The 'REAL' thing is a desktop app which does allow saving data to local (sqlite) files (and yes, there are additional entries in the menu for this).
Just to confirm, the concept is basically...
"I'll create the software X to fit my own specific requirements/needs, then I'll see if anybody else wants to use it as well (which would mean that that niche of people have the same needs/requirements), and if that's the case then I can decide if to put more energe/effort/$ into it otherwise it will just be something useful for myself"
..., right?
I think that for that to work the important detail about the concept&implementation is that the SW must be complete (~no critical bugs, all needed functionality is available) + not reliant on any external dependencies (e.g. hosting, downloads of data like Tax rates from anywhere, etc) + must use proven and stable technologies. A stupid example would be "Tiddlywiki" (https://tiddlywiki.com): I downloaded the html/js-file (proven & stable & compatible with all browsers) and it works with 0 external dependencies => I can be sure that I won't loose my notes whatever happens and that the full functionality will be always available, even if in the worst case I don't have an Internet-connection.
Btw., the GigoBooks app does not currently allow to save data, or did I overlook some menu-entry?