New construction: Connection & cabling Internet + TV

Internet:
I would do it similarly to you. If your current contract expires and the DG is not finished yet, I would try to get a contract with a monthly cancellation option. I don't know to what extent your contract continues if it is transferred to the new building. But if I read that Telekom will grant you a 300€ builder credit, then I assume that a new 24-month contract period will start again. Maybe forgo the 300€ and get something cancellable monthly.

TV:
Satellite is basically free. Only the private HD channels cost extra.

Network Cabling:
Just don’t let your general contractor or electrician fool you: "Nowadays everything is done only via WLAN!"
WLAN belongs in the house for mobile devices. Ideally with access points centrally arranged on each floor.
All devices that are stationary belong to LAN for me. As previously mentioned, at least 1 double socket (fed with 2 cables) per room. Office and TV possibly even 2 double sockets.

The LAN cabling for devices and access points is becoming increasingly important as internet transmission speeds get faster and workarounds like PowerLAN (DLAN) and repeaters slow down the transmission speeds. And we won’t even talk about network stability.

I see it the same way with the LAN cabling. It will of course be a bit more expensive, especially because we can't do it ourselves, but I'm happy to invest in that. Especially since we want to watch TV over the internet (DG), it should at least be possible in all living rooms.

I have no idea about the access points. Until now, I only knew that the router itself was the starting point. If my kids' room was too far away back then, I just had bad luck. So access points are basically small mini-routers that you put in every room!? I will read up on that some more.

About TV: DVB-T2 is apparently something different from SAT and doesn't require a dish on the roof. So if my TV is compatible with DVB-T2, it simply receives it without "extra hardware". If I understood that correctly, that would be the optimal solution for my transition period, without a big contract, without much work or money invested!?

DVB-T2 is basically antenna television. Depending on the region, it has a very limited selection of programs, but it is indeed an alternative.

The DG reimburses you, if I remember correctly, up to 12 months of contract costs with the old provider. Therefore, the risk is also reduced with the 2-year contract. I also use IPTV. However, I do not want to rely solely on it. Unfortunately, IPTV is more prone to failure than, for example, SAT. I can't imagine what my wife would do to me if the TV were to fail just before the bachelor final. Since I still have a SAT dish, I could simply switch plugs. I would be equally quite pissed off if the TV were to fail during a World Cup final.

DVB-T2 is basically antenna television. Depending on the region, the program selection is very limited, but yes, it is an alternative.

I checked it once on the dvb-t2hd.de site with the following result (see picture). So for the private channels, I would have to install something outside the house after all?

If I remember correctly, the DG reimburses you for up to 12 months of contract costs with the old provider. Therefore, the risk is also reduced with the 2-year contract.

I also use IPTV. But I wouldn’t rely on it alone. Unfortunately, IPTV is more prone to problems than, for example, SAT.

It’s unimaginable what my wife would do to me if the TV would go out right before the Bachelor final. Since I still have a SAT dish, I could just switch over.
I would be just as pissed if the TV went out during a World Cup final

The part about covering the costs is correct. Of course, that reduces the possibly double costs, but of course, I would prefer a solution where no double costs arise at all...

Good to know. Intuitively, I would have thought IPTV to be the most stable. But of course, internet outages can occur depending on the provider, and in that case everything goes down immediately. Really not an easy decision...

SAT TV is contract-free, you also receive RTL and others, just not in HD. Arte, the 1.2.3., three Sat etc. also in HD. Again GigaCube VFone, Flexx variant. You only pay in the month you use it, it was 39.95 here. When LTE is available, it is super fast, like DSL 16000. Good workaround. Access points: No problem. We do EVERYTHING WLAN and miss nothing. Also smartTV works wirelessly great.