Some phones come with an infrared (IR) blaster. Check the specs of your phone and just use that if it has one.

Schau nach Schulbüchern. Dort sind einfache Grundrezepte mit Theorie üblich.

https://vdo.ninja/

• Bring live video from your smartphone, remote computer, or friends directly into OBS or other studio software.
• We use cutting edge Peer-to-Peer forwarding technology that offers privacy and ultra-low latency

https://dearrow.ajay.app/

Beware that it can make the stupidest videos look interesting.