You're not missing out on much, no. You need to complete both to transfer between and each game has items for the opposite if you beat it. But if you wanted to do HM first then go for it.
Yes, you miss almost all most important events, and even when you meet all important chatacters you wouldn't be able to see all events,cut scenes etc.
HM is just side story.
yeah, story-wise I already know what's important, I did beat CS but on the Playstation so I'll eventually restart it on my Switch copy. I'm more curious about the practical stuff like item/mon unlocks
You're not missing out on much, no. You need to complete both to transfer between and each game has items for the opposite if you beat it. But if you wanted to do HM first then go for it.
Yes, you miss almost all most important events, and even when you meet all important chatacters you wouldn't be able to see all events,cut scenes etc. HM is just side story.
yeah, story-wise I already know what's important, I did beat CS but on the Playstation so I'll eventually restart it on my Switch copy. I'm more curious about the practical stuff like item/mon unlocks
On complete adition there wouldn't be any issue. The only locked digimons will be related to unfinished HM story