I have a Linux Mint VM, where I installed formerly NetBeans 12.x (up to 12.6) and now I've updated it to 13.0, all with flatpak, and even starting from a clean setup.
With all those setups, NetBeans can't find Mercurial, even if I really have it in /usr/bin/hg available and working (when used from the shell).
From menu Team / Mercurial / Initialize repository... I get the error "Mercurial could not be found", asking to check PATH.
The strange behavior is that if I even browse for Options and Mercurial Executable Path to /usr/bin I can't see hg in there, while it is in the filesystem!
Is NB browsing somewhere else when I open /usr/bin?
Is it accessing some virtual environment? I'm confused
I have a partial solution: the flatpak package is indeed at fail, as for some reason it's not seeing my /usr/bin but a virtualized (?) directory, where many files are missing - notably hg and hg-ssh
So I removed the package suggested by the Linux Mint Software Manager and installed the package got from the Apache NetBeans site, similarly to what @flied-onion did.
What's still missing is that NetBeans relies on the hgk application as an hg GUI interface for some functions (see Team / View). This is unknown to me, and I don't find it in any (recent) Debian flavor.