The Linux hyper-v vss daemon freezes file systems per default: https://github.com/torvalds/linux/blob/master/tools/hv/hv_vss_daemon.c
You’ll have to modify this one if you want to execute scripts.
This is all way out of scope since you decided not to run UrBackup in the VM.
And if you find the veeam scripts, you can just use those. The blog entry doesn’t help on that front. Note that Veeam has it’s on Linux kernel module to snapshot, so the link above might not even apply to Hyper-V.