Well, I think it's fantastic that you are learning about vaping for your dad. Might want to ask him a few questions if you plan on doing most of the legwork-- Like, would he prefer tobacco flavors (my husband wanted that so I got him some NET (naturally-extracted tobacco) juices which can be a bit pricier but offer that "true" tobacco flavor. Some folks like the idea of "tobacco" e-liquid, I personally was quite Done with the taste of tobacco when I quit, and lean toward fruit and desert and alcohol flavors. There's a surprising amount of options out there.
If your dad is mobile and open to it, a trip to the vape store might be in order at some point, with that said, gathering as much background information as you can about it first is smart, before presenting it to him.
There are some useful pinned links scattered about and I also have a feeling Brother Bob will be along and give you some great links to information and threads that will help you get started (he's kinda well, I call him the patron saint of the New Member's forum, but he's great at identifying helpful information and then posting it for your perusal.
I will be wishing your dad takes to vaping like a duck to water, but often times it takes some trial and error (and dual using) to really get going with vaping, so just continue to be encouraging (but not all over him) as he experiments.
That's how I got my husband to start vaping. I just shut up, vaped, watched his increasingly pitiful attempts to quit, and he eventually asked for my help. So also understand that regardless of how much you love your dad, ultimately he will need to do his part, once you help get him going but either way I commend your efforts.
Funnily enough, MY son, who briefly smoked, then vaped for a while, gifted me his gear when he quit
vaping. That shamed me enough (along with my ever worsening health) to give it one more try, and I am
so glad that I did. Keep posting until all your questions are answered
Anna