Well you run into a trap of the PiHole uninstall script. You removed the critical system dependency and cut-off the network. Don’t worry you are not the first one. We ask PiHole guys to change their uninstall script. They acknowledge the issue but no change so far information.
Theoretically there might be a way to install some package offline. But this would require physical access and a screen. Btw what system you are running?