I don't have WSL in front of me at the moment, but going on the assumption that you're using the Ubuntu environment atop WSL, I tried to replicate your condition on an Ubuntu 18.04 LTS VM here:
Command 'gvim' not found, but can be installed with:
sudo apt install vim
sudo apt install vim-gtk3
sudo apt install vim-tiny
sudo apt install neovim-qt
sudo apt install vim-athena
sudo apt install vim-gtk
sudo apt install vim-nox
Did you trim the other outputs from that command, or does the command truly only tell you about the
vim package under WSL?
APT is guessing here, based on the command name you tried, not prescribing. Some of those options will get you something like what you're expecting, and some won't; you're expected to be able to make the distinction. Of the options, I'd recommend
vim-gtk3, but another might please you better.