Hi,
Fletcher rightly mentioned.
We say "The shop is open...." for giving information about the state or condition of something. This is one usage of the verb "to be".
But if you are using the passive form, then the shop is no longer the focus of the attention which because of this we don't use this sentence in passove! (As simple as that).
If you use the passive form, either the previous sentence or the next sentence or adjunct (or complement) is the focus.
For example, the shop is opened after the pandemic. Here the phrase is the focus.
The shop is opened again by the mayor.
A quick note:
The shop is opened from 6....
You can say this sentence but here you are not emphasizing the status of the shop (being closed or open). But, actually you are conveying that at 6 o'clock the shop was open ( the focus is on the time and not on the status of shop as being open or closed).