I think the shared build service would be too much effort for the size of the project.
A build service is not really much effort, they are pretty simple actually.
It’s also not wanted that the user can set the Input manually, because its a calculated value (Git States etc).
Which is a point for build service, not against.
Is there something to be considered bad of simply just using
Yes, any usage of “extra” properties is considered bad and usually just a work-around for not doing it properly. But well, whatever works for you. 