Correct. Those are the available options.
if i do the in-app purchase, do you know what will happen with linking my SketchUp account
An in-app purchase will be associated with whichever Apple App Store or Google Play Store account you are signed into the respective app store with. There’s no way for us to know about, or link standalone in-app subscriptions that are made through app stores to any info we manage about your SketchUp product purchases.
The Shop/Pro/Studio bundle subscriptions are the best way to make sure that access to all of the products offered in each of the respective bundles are managed in a consolidated way.
Reading between the lines, I’ll offer that if you’re considering the possibility of in-app subscription now, and Pro Bundle subscription later–that’s a viable option too. In that scenario, however, you’ll want to make sure that when you transition to a Pro Bundle subscription, you then cancel the in-app subscription via the app store you purchased it from.
Hope that helps.