Bill Denton wrote:

I am not sure what your point about VFR-on-top is, but as a reminder to
you, in the US VFR-on-TOP is a specific IFR clearance that must be
requested.


And if you are granted that clearance, you will be flying under what are
essentially Visual Flight Rules, you will be allowed to deviate from your
as-filed flight plan,

No. You must follow the flight plan just as if you were regular IFR.
Slight deviations for cloud clearance are OK. If you want a different
route then you must ask for and receive a new clearance.