Quick and dirty: Buy a domain name. Create an account on Cloudflare. Update the DNS for your domain to point to your home IP. Enable the "Proxied" button. Your IP is now behind Cloudflare. Now, when your IP changes, you'll need to update this. I am doing this automatically via a script I wrote. It runs on a server I have, but I used to run it on my node. This requires a little more work, but not a whole lot. You'll need to do some other things though to, this gets a little tricky. You'll need to run Nginx, you can run this on another computer/server/node you have or on your Umbrel. You need to setup a reverse proxy to point to your node and BTCPay Server. You can find guides on how to setup Nginx and reverse proxy. This is the only hard part and will take a lot of work for someone that isn't familiar.