Selfhosted

With SSH it is easier to do key authentication. Certificate authentication is supported but it is a little more hassle. Don't use password authentication as it is deprecated and not secure.

The key with SSH (openssh specifically) is that it is heavily audited so it is unlikely to have any issues. The problem is when you start exposing self hosted services with lots of attack surface. You need to be very careful when exposing services as web services are very hard to secure and can be the source of a compromise that you may or may not be aware of.

It is much safer to use a overlay VPN or some other frontend for authentication like mTLS or an authenticated reverse proxy.

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.

Presuming you have not limited edge port 22 to one or two IPS and that you are not translating a high port to 22 internal, the danger is that you are allowing the entire internet to hammer away at your ssh. If you have this described setup, you will most definitely see the evidence of attempts to break in in your SSH endpoint and firewall logs.

Zero days for SSH do exist, so it's just a matter of time before you're compromised if you leave this open.

Imagine opening all the windows in your flat. Then leaving them open for a month. What would happen? How many insects would make their new home in your home? How many critters and cats would do the same?

Now, each window is a port. Your flat is your network. Each critter or cat is a bad actor. Each insect is a bot or virus.