This is not going to be easy, considering that one would need to hide its presence from several low and high level tricks, rather than only from human eye.
Some food for thought: GitHub - a0rtega/pafish: Pafish is a testing tool that uses different techniques to detect virtual machines and malware analysis environments in the same way that malware families do
And related entries, e.g. from the most recent issue in that repository: How anti-cheats detect system emulation | secret club