How can I coect devices on multiple networks to one VPN to control them remotely?

Here's the challenge:

I will be installing 10 TV screens into 10 different locations in my city. These are WiFi-enabled smart TV's that can be controlled via a software called MDC (Multi Display Control). MDC can only coect to screens that are on the same LAN. The problem is that I need to control all of them from a remote location.

I will be able to use the locations WiFi, but will not have access to their router settings.

What I've come up with:

I'm not a network engineer, but I have been around computers for a while. This is my potential solution...

I believe that I will need to create a VPN. The "smart TV's" can coect via WiFi or Etheet and have basic network settings (IP, Subnet Mask, Router and Proxy Server). I will need some sort of bridge between the screen and the location's router. I think configuring a Raspberry Pi as a VPN client will be the simplest solution.

1. Each TV will coect to a Raspberry Pi via Etheet.
2. The Pi's will be coected via WiFi to the location's router.
3. The Pi's will be configured to coect to a VPN.
4. On my end, I would set up the VPN server on my network using OpenVPN.
5. Coect with using MDC to the screens that now show up on my local network.

I've never done something like this before, do you think this could work? Is there an easier solution?

The main limitations are very little control over the various location's networks, provided only SSID + PW. Visiting the location to make changes at a later time will be extremely difficult. So, ideally, the VPN is hosted elsewhere and I coect to it with the MDC-host computer. That way, if the VPN server changes, I don't have to reconfigure all the Pi's. I'm on a budget too, so low cost is important.

I'm sure that this can be done but have very little idea about the most effective way to do this.

Any ideas on how to improve my idea? Is there a much better way to accomplish this?

Thank you for your time!