Make water pipe from cistern frost-proof

It is best to install a proper irrigation system right away. Depending on the garden, it is not much more work than installing a few tapping points. These are blown out anyway in autumn. Therefore, there is no need to worry about frost-free installation.

Thank you very much for the answers!

Whether to stick with the hose or lay pipe, I don't know yet, as it won't be decided until next year whether we will add a garden shed and set up a tap there.

Either way, it seems I need the T-piece with a valve and have to empty everything in winter, so I will do it as and described. First, cut the hose at the blue circle and install the T-piece, empty in winter. Probably a quick coupling would be sufficient for the hose.

Later, when the planning and all withdrawal points are finalized, upgrading to pipe is tempting. Many thanks at this point to for the keyword "PE-HD pressure pipe."

There are already some posts regarding irrigation. If you need help, just ask.

I will control my pump via the Smart Home anyway, so that my weather station automatically shuts off the pump at subzero temperatures. Additionally, I am considering whether to also drain the pipes using an electronic valve for this drainage.

Do you have anything planned in this direction?

You don't have to control the pump via smarthome but the valves. The pump detects the pressure drop and then starts. For the pump, just an on/off switch. This can of course also be realized via "smarthome".
Because of the weather station, you will stop watering anyway before winter. The individual zones then need to be emptied. Easiest with compressed air and then cycling through the valves. Goes quickly.
We are also planning automatic irrigation. But with a large pump, thick pipes...
A total of 28 valves/zones.
A valve will be installed in the cistern/pump outlet. But for manual operation. In autumn, it makes sense to check the cistern anyway to see if the bottom needs to be vacuumed...
An automatic valve in a 60mm pipe would also be too expensive for me. Especially since it probably wouldn’t work reliably with annual operation.

I see it like Rick, I don't need smart home at this point. I will get the water level via a sensor, but I will operate the valve or the quick coupling manually.

A large irrigation system is currently not planned, only 1-3 withdrawal points. Maybe later, when I get bored, but right now we are fully occupied with the construction.