3.7 on apple silicon

You can go fetch the Python.org installer for Python 3.7, if it's still available, and providing it is a 64-bit installer. These are formal macOS installers and do not require any package manager. It won't step on any System Python, and will link the Python.framework binaries into /usr/local/bin as python3, idle3, etc. Adjust your PATH statement accordingly.

With the release of Python 3.9.2, Python.org is including a first universal binary for Apple Silicon Macs, This is what I have installed on my M1 mini.

If you install Apple's Xcode 12.4 or Command-Line tools for XCode 12.4, it will install another System Python 3.8.2 (additional to Python 2.7.16) as /usr/bin/python3, so beware, and again, your PATH statement can help you avoid running that turkey.