Best of luck on your new hobby!

I didn’t see anything in your post that set off alarm bells

If you’re looking to save some cash and your ISP gives you a stable public address you could utilize a Dynamic DNS provider (ala duckdns) instead of registering a domain

In the states the company running the payment system (Visa, Mastercard etc) is a separate company than the supermarket and so they can’t necessarily group together all the purchases a single customer makes, let alone if they pay cash

Imagine a taxi driver, he might overhear your name and the address you’re going to, but that doesn’t mean he can go look up every taxi trip you took,

Now if you have a loyalty card there’s a single identity to group and market towards

Now take this all with a grain of salt, your system may be different, but the technique spread across markets

All hail Hank of Green, King of slop