How can I print to my home printer when I’m not at home...?

normally you can't unless one setup a VPN server so your ios device act as it was connected to your LAN network across the internet

This may depend on your printer. I use a HP printer. When you first set up your wifi printer, it should come with the facility to configure an email address for the actual printer - which you can change - and you can then email your photo/document etc to your printer, so that it can then print off. So mine for example is f*****************@hpeprint.com. If you don't remember what your printer email address is, go to your printer's web page, and register or sign into your account, and take it form there.

You can't. Airprint requires the printer and iphone be on the same wifi network.

a super tech nerd or it admin or somebody who pay somebody to set it up are realistic scenarios.

https://www.howtogeek.com/221001/how-to-set-up-your-own-home-vpn-server/

more

https://www.google.com/search?source=hp&ei=ziSFXLCiPI2ukwWl04S4DA&q=set+up+private+vpn+from+router&btnK=Google-s%C3%B8gning&oq=set+up+private+vpn+from+router&gs_l=psy-ab.3..33i22i29i30l2.826.826..1032...0.0..0.113.194.1j1......0....2j1..gws-wiz.....0.fYA7UHSmXBw

but as deggie state:

I have a netatmo weather station and security cam and some dlink security cams

both can be accessed by apps on my iPhone because the devices connects to their manufactures clouds and the ios apps can access them that way without the need for VPN

a printer could work in the same manner if the manufactures implement a similar system

so if you name your printer brand / model to deggie , you may get some info as to if there is a solution in that direction.

You would need to see if your printer manufacturer offers an app that allows this or a way to used email to do so.

Not sure you can do that with AirPrint.

That would depend on the make and model printer you have which nobody here knows.

https://support.brother.com/g/b/contacttop.aspx