ok, so. going through the process for a hosted VPS is waaay overkill in most cases.
The easiest way to get this working with a dynamic public ip address is to use a DynamicDNS provider.
There are heaps of them.
I've seen a number of modem/routers that have the option built in to them. You just sign up with the free DynDNS service, input your login details in the correct area on your router and it'll handle it for you.
Some will have a client you can download and run on a computer that checks the IP every hour or whatever.
The PiVPN even has an area talking about them and it looks like basic instructions for a client to use.
https://docs.pivpn.io/faq/
Now, the one issue with this is if your internet connection is on CG-NAT.
This is very common with 4G/5G connections and on the home plan of Starlink.
Do you know what your internet connection is?