I’ve only played around with it to learn and never had a reason for on chain. But I thought there was an option that would steer you in one direction or the other based on size but I’m probably wrong. It would guess you’ve already researched it.
Discussion
I didn't research it myself tbh. I never tried this plugin I just assumed this feature was not in yet.
If you setup an onchain hot wallet using BTCPayserver, the option to direct the payment would happen when generating the invoice to pay and I think it would simply bypass the Lightning address creation and instead create an onchain address. My current nod doesn’t have a hot wallet tied to it or try it. Since the strike plugin would only be for lightning, it wouldn’t happen on Strike account.