Front door for garden house - rough dimension

Hello,
I am currently building the walls of my garden house and will probably build the front side on Saturday. A front door is to be installed there. For cost reasons, I would prefer to use a standard size. Can you generally specify the opening size for a door width, or are the rough opening dimensions standardized?

Is a side entrance door of sufficient quality for the garden house or do you need a "real" front door like in the house? The former can already be bought cheaply at any hardware store in various standard sizes. Take a look at the options and then brick up the front accordingly. Or configure it at various shops. For example, in the configurator with further information on the required rough opening size:

I think a PVC side entrance door is sufficient. But they certainly have the same dimensions as a front door, right? The room exterior measurement is then the distance between the reveals, or is that the exterior width of the door and I have to add something to it?

I think a PVC side entrance door is sufficient. But they surely have the same dimensions as a front door, right?
Is the room outer dimension then the distance between the reveal surfaces, or is that the outer width of the door and I have to add something to it?

You have to check the rough opening = the necessary opening ==> it is specified by every supplier. The room outer dimension doesn't help.
See above.

Thanks in advance for the advice.

I have my eye on the Meeth Kunststoff front door Signum PVC 32. It costs only €399 in the DIY store at a width of 110cm.
On another site, the rough opening size for this door is given as 112cm, so about 1-2 cm on each side. Unfortunately, with the current garden shed width, I am 6cm short. How can I best compensate for this?

[*]With the insulating block? That would involve a lot of cutting.
[*]Or can I finish the width with the block and reduce the 6cm later? If yes, what is the best way to do that?