We used to travel often, both in our motorhome and otherwise, and I used a VPN whenever connected to a public wifi network, such as in an RV park, airport, or hotel. I never used ExpressVPN, but this article has quite a story about it, and some other VPNs as well. Not good 'stuff' about ExpressVPN, to put it bluntly. It's interesting to note this is the VPN Kim Komando recommends in her technical emails and broadcasts. Will be interesting to see if she still recommends it after she, hopefully, reads this article.
A VPN will protect you from a hacking by someone on the same public wifi network as you are, but one must remember the internet connection will still go through the VPN's server, somewhere, and operators can then have access to your message. Realistically, this never bothered me as I never sent anything I wanted to remain confidential over a public wifi network, like credit card info, etc.
I hardly ever use a VPN anymore, as the pandemic has slowed (stopped?) our travels, and our home network and router are secure, but I find articles such as this interesting.
Jim Hamm