Mailbox with or without parcel box?

I don't see any disadvantage if the couriers use the box without ringing. I even think it's good. It's more comfortable for the courier and you yourself are not disturbed.

I don't either, but the OP says that he wishes the box to be used only when he is absent.

With us, they put the stuff in the garage. No problems.

I looked at many but most that were still roughly within size and price range were way too small at the "insertion hole"

At most a DHL M parcel would fit in there, so the size doesn't really help me

Just near the packstation and done... a normal mailbox is enough and is also affordable

At our place, they put the stuff in the garage. No problems.

Is your garage open?

For us, it varies a lot. DHL delivers directly or brings it to the branch. But they are also not under stress.
Amazon comes with their own drivers, who put the package on the terrace or in front of the door if we are not there. However, they ring the bell first and often come only in the afternoon or evening, when we are often home.
The worst are DPD, who just leave the package, even though we have explicitly stated in writing that they are not allowed to leave it. Almost always the same delivery person comes, who doesn’t even ring the bell. I have told her several times that she should leave it with a neighbor if we are not there. She said she doesn’t have to. Complaints don’t help. Therefore, we try to avoid DPD, and if the dealer only offers them, I sometimes write to the dealer.
We once considered a postbox but dropped the idea again, as it is actually not necessary.

, not open, but also not closed, so you just have to lift the gate briefly.

The parcel courier should only be for packages when we are not at home

I currently don't know if the neighbors are even home during the day to receive packages and if they would even do it.

They feel the same way as you do. Everyone needs sugar, eggs, or someone to check on things sometimes through informal channels, and yes, also someone to look after the mail. Or water the flower pots.

So would you rather say without a parcel box?

If you can't afford a butler or caretaker… but don't want to trust anyone, then decide what you need. We handle it through a neighbor WhatsApp group, which existed from the beginning with our immediate neighbors (for delivery service I also give the neighbor's address by email if necessary) or I spontaneously change the drop-off location by email. If I miss it and we are on vacation, then he also goes around the house and checks everything. My advice: leave it.