Okay, this is a recent discovery (and the first tip to be cross-platform): Tailscale.
Tailscale is a VPN but not in the way you have come to known VPNs, it doesn't have central servers that it routes all your traffic through. You can route all your traffic from your current device to all the devices that are in your Tailscale network though. So if I'm traveling in the UK, I might want to watch Danish TV and make my home PC the endpoint so that the Danish TV channel knows I'm streaming from Denmark.
That's not what I'm using Tailscale for, however. It is actually (currently) only in use by me for the one beautiful feature that you might remember from a piece of software called Hamachi (now part of LogMeIn): creating a private, routable network between all my connected devices.
But what does that mean? Very simply: I use it to set up a Remote Desktop between my home PC and my laptop and vice versa. I can also use my Android phone to RDP into either computer if I wanted to.
This bypasses all the horrible manual configuration I'd have to do otherwise to tell my home router that people from the internet are allowed to try to connect on port 3389 (yikes! major security concern). Tailscale makes a private network, you need to both be connected to it, otherwise no dice.
Of course it's even more fun the other way around: I work in a coworking space and I will never ever get permission from the network admin to open ports into the network. With Tailscale, I don't need to care, I have a perfectly fine private IP address to connect to (in fact, it magically also maps to my computer name so I don't even need to know the IP address) and the network admin didn't have to configure anything.
Recently the Tailscale team released an SSH client in Web Assembly and here is where it gets WILD. Any browser in the world suddenly becomes part of your Tailscale network (after securely logging in). A little more info in this video from Christina Warren:
This means any computer now can be part of my personal Tailscale network and I can RDP into any of my other computers that I allowed before. Or SSH or.. you know, whatever I've opened up.
I have only explored this very little but it is a tiny app, it is FREE and it runs basically anywhere. After using this for a few months it is also very stable so I don't worry about suddenly one day not being able to connect.
Fun fact: I'm a YouTube Music subscriber, using the YouTube Music Desktop App which allows for phones to connect to it by IP address, so any phone becomes a remote control for my music. At work, this type of usage is not available because every device is on it's own subnet. Connecting the phone to Tailscale though.. gives me an IP address to connect it to and.. presto!