Oat condensed milk substitution?

Thanks for the info

I've used condensed coconut milk successfully. Though I haven't used the oat version, I think it's worth a try

Agree with Nancy but if you don't want to experiment I am sure you can find similar recipes that are vegan which would be made with alternative milk.

Haven’t done it, but see no reason no to.
Suggestions - compare nutrition values on the dairy and oat condensed milk in case you need to adjust some values to match (thinking especially of fat and sugar).
Make a smaller (half or quarter) pie, as a test batch, to see if taste and texture are ok or if they need adjustments.

Good luck and please add notes to the recipe on your outcomes.