It shouldn’t make much difference.
The communication to the bank should already be encrypted because the bank should be using https.
Adding VPN is just adding more of the same.
All other attacks, like phishing (being lured to access a site which looks like your bank), *********s etc works just as well over a VPN.
Adding a VPN is just like adding a second lock to your door while the windows are just as easy to open.
The same goes for online shopping.
Just make sure the site are using https.