Best languages for On-Prem server apps concealed?

Dumb noob question but I’m starting a business with my colleague. One app we’re making involves running a server either on a docker or the desktop. I was gonna say let’s do Python so it’s easier to deploy. But now I’m worried our source code is literally there for anyone to take and alter.

I’m guessing I have to opt for c++ then or has someone already tackled this dilemma?