I've tried both VanillaOS & Silverblue and they are okay for development. It has been a while so maybe I don't know but it was a little painful to install things on occasion back when I used it. If you are okay with using a lot of Flatpak and can make your workflow out of containers then I think you'll be good.

Welcome to the world of Linux!

Yes, every modern operating system today can run Git and SSH. You simply have to install Git (if not already installed by the OS) and you are ready to go.

Git Documentation for Linux-Installation

To install git you can use the package manager for your distro, for VanillaOS it is apx and for Fedora it is dnf, those are used in the Terminal maybe you will also find Git inside your GUI-Package manager. Vanilla OS is based of Ubuntu, so you should have no problem finding a working release, when you find no Git-Installation via apx try the apt one.

SSH will already be installed and configured, it is a default functionality.

If you have any questions regarding the installation or Git-Use, just make an other comment.