I am going to set up my own bitcoin node with a rasberry Pie and Umbrel. Now I saw that Umbrel also offers other cool solutions like running your own server or cloud. Can I use these services as well via the rasberry pie? Or will this lower the security of my Bitcoin Node?
technically a bug in this other software could give a potential of higher risk. but: it‘s not likely
also still open source programs and mostly password or even 2FA secured. but still a little less security because of that
hopefully umbrel will give us a bitcoin only software in the future for maximum safety even this is also very cool to do much more with your server. everyone should decide that by their own. for me i like to enjoy the other apps very much
cheers
You have to understand what you are doing. Raspi is not Rambo.
If you have 4GB ram you better only run a btc node and lnd and electrs, and maybe few relevant apps, like mempool, btc rpc explorer and ride the lightning. More than that and you will soon join the clouds here complaing about mysterious crashs… 
Even with 8GB, you will have limitations with SSD soon getting full and perhaps in a few time SSD failure, because it is a disk not indicated to servers, they have limited writing number life.