Lmao, the PS4 digital games surely sell magnitudes better than their Vita counterparts, so the placement doesn't matter in this case when we don't have numbers.
Not to mention PS4 SKU crushed the Vita one on every PAL Chart (and will in NPD) if the latter even had a release since it's not really worth it considering no Vita retail games sell anything significant anymore in the West.
1. Vita Digimon didn't have a physical release in NA or Europe. Please know what you're talking about before using such definitive words as crushing. Being on PS4 doesn't mean guaranteed sales, and this has been proven time and again. See Tearaway and now Gravity Rush. Curb the fanboyism.
2. If we look at the kind of games above Digimon PS4, games that sold because they were on sale, we can probably get a good idea of where Digimon Vita would place. Considering prices, audience, and availability, I'd wager it would probably fall somewhere between NBA and Life Is Strange, being a niche JRPG released in a digital-exclusive format.
Also considering the placement of SAO Hollow Fragment on both platforms, being the same price on both systems, the PS4 version probably sold slightly better due to being a newer product. Looking at its placement compared to Digimon Vita, it sold significantly less there, while the PS4 version sold slightly more than Digimon PS4.
So yes, it's very likely that the Vita version of Digimon sold more than the PS4 version digitally. Sorry.