Honestly, that's a pretty niche pairing. It's not one I've actively searched for, but I've stumbled across a few takes. The obvious place would be Archive of Our Own, filtering the 'Dragon Ball' fandom and then using the relationship tag Goku/Vados. I'd be surprised if there's a huge volume, though. Wattpad might have some, but the quality there can be super hit-or-miss, mostly leans towards fluff.
What might actually yield more is searching for general Vados-centric fics and seeing if Goku shows up as a secondary pairing. A lot of writers who like her character explore her dynamic with various Saiyans, and Goku's the most obvious candidate. Sometimes they tag it, sometimes it's just a background element. I've seen a couple where it's more of a slow-burn cosmic curiosity thing rather than outright romance, which honestly fits both their characters better to me.
I remember one specific fic on AO3 that was tagged as Beerus/Vados but had a significant Goku-Vados subplot that was really well written, almost philosophical. So maybe expand your search to include fics where they're both present characters, even if not the main ship. Finding exactly what you want might require a bit of digging through related works.