@c46 :- Hallo.....and welcome to Linux.org.
Depends on what you want to do remotely. For my occasional needs, I find this site provides what I need:-
DWService offers a service that allows remote access to systems using a standard web browser.
www.dwservice.net
You install a small piece of software called an 'agent' on the remote machine, which does nothing else except listen out for an incoming data stream on one specific port; this can be started remotely if required. Then you simply view and/or control the remote desktop through your browser.
Or there's this:-
Instantly access and control desktops from any web browser. Perfect for IT administration, technical & customer support, and more. Unlimited concurrent connections and easy integration.
getscreen.me
.....which, again, works in very much the same way. Yah, I admit; it's the lazy man's way of doing things, rather than messing around setting up a highly-secure VPN.....but for occasional, 'ad-hoc' use, they'll do the job quite acceptably.
Both do use end-to-end encryption, which does add a layer of protection at least.
If you want a dedicated app, you could do a lot worse than take a look at AnyDesk:-
Discover AnyDesk, the secure & intuitive remote desktop software, and take advantage of the application's innovative features!
anydesk.com
We gave up on TeamViewer several years ago in Puppyland, and moved to Anydesk as our primary replacement.....though of course, with this one you MUST have it installed at both ends, a la Teamviewer. It's easier to do this stuff on-the-fly with the browser-based ones; just give your 'client', 'pupil' or whatever a URL to download the agent, and within minutes you can be helping them with whatever needs sorting out.
Mike.