Not a sysadmin, just a casual IT.
If it is open, it is going to get hit by scanners, scrapers, everything and the sun, even if it is secure. Generally, 443 for your websites via reverse proxy with an IP whitelist + password is okay. Not special, lets you add subdomains, very convenient.
Now, there isn’t anything special about any given port, but you still need to have some form of access control that you need to set up. If it is an API have some sort of API key in place. Implement 2FA. Try to isolate the service from the machine. Isolate the machine from bare metal. Keep the bare metal machine isolated from your home network. Take up farming. Change the default port and add some form of access alerts/logs. Have some sort of fail2ban service in place because you will be firehosed with scripts and bad traffic.
Maybe some of the stuff I recommend is paranoid overkill, but I don’t know enough to cut corners. Security is a hassle, a breach is a nightmare.
… Which is why historically it is used as currency… kinda burying the lede there.
Bottle caps (fallout franchise), cigarettes, ramen packets (prison), sea shells (aka wampun in some Native American Cultures), salt (early scarcity) and gold are “valuable” because they are used as currency, where they are given value in excess of their actual ability to be used.
These attributes are not specific to gold alone, many other metals, jewels also share the same attributes of being able to used as currency due to their ease of division, relative scarcity and not rot aka “ability to store value” as the egg heads say.
Suffice to say, gold isn’t valuable because it is gold (I can eat a ramen packets, smoke a cigarette) it isn’t valuable because it is backed by. the government (we explicitly use it because it isn’t fiat) but rather it is valuable because IT WAS MONEY, because carrying 500 cheese wheels isn’t a thing irl.
I can point you to further reading, but just about all MacroEcon text books will cover this in the first chapter.