I never like pauschal Trip from Travel agency either. It's too unflexibel.
I prefer do things and choose places to visits or events to experience my self.
I don't always want to visit all the popular places.
Well...maybe you could still do the e-Travel declaration at home (i think you can Do it 72h Prior travel), and then just print it out.
This way you don't need to install anything on your phone nor show it to the border control officer.
TBH, they don't always check it either.
Not every country is that strict.
When we went to Indonesia last time:
The flight attendants and Transit check in staffs would remind us about this and can give assistants too about it.
However...when we landed, it was not checked LOL. I wonder if they just do random checks or if we have something to declare.