Install flatpak with the following command:
vpm install flatpak
To get flatpak working, you have to connect with flatpak database by the following console command:
flatpak remote-add --if-not-exists flathub https://dl.flathub.org/repo/flathub.flatpakrepo
To get flatpak working, you have to restart VoidPup.
I have done this with VoidPup64-22.02-240717 and flatpak 1.15.10.