Anyone know of an app or push service that can notify when vbyte fee hits a certain threshold? For iphone

Coldcard experts, for purpose of setting up a watch only wallet, what’s the difference between using the “Dump Summary” method vs “Export Wallet” method of passing the xpub? Reason I ask is because it seems to be easier to generate a QR code via “Export Wallet” method than generating a file via other method then trying to get that onto phone and into app. But I don’t want to somehow screw up and pass along info I shouldn’t