I am trying to install Youtube on a Rpi 3b+ but I get the fake apps (like Youtubuddy).Can I install Youtube on a Raspberry pi without running youtube in a browser ?
I don't know the reason why you want an app, but I will assume that you want to separate YouTube from your main web browser. In that case I think a site specific browser is a good solution. It will work (almost) like a dedicated app.
Below I have listed a few options that are available on Linux. I have not tried them on Linux myself, but I have tried them all on macOS. Most of them exist for Windows also.
Ferdi (FOSS) https://getferdi.com
Epichrome (End of support) https://github.com/dmarmor/epichrome