Is it possible when i play with the nintendo switch on the tv, to transfer my tv screen to my laptop?
Short answer again, no, not without CaptureCard.
So do you want to watch TV on your laptop while playing Switch on the TV? Do I understand this in the right manner?
You need a capture card in / on the laptop for this. You either have one with an HDMI pass through or you use an HDMI splitter.
Yes
https://www.amazon.de/...00FMS3KYS/
Unfortunately it's sold out, but you'd need something like that if you at least want to see Prosieben or something.
Otherwise, you can also watch many TV channels in the live stream. You don't have to connect the TV to the lapi for this.