But I did have issues with some Web SDRs on http://www.websdr.org/ when using Chromium-based browsers

And I wasn’t the only one, looking at F.A.Q.:

Q: I’m using Chrome and don’t hear audio (on some sites)!

A: Since version 71, Chrome does not allow every website to start playing audio, in order to stop annoying advertisements. Chrome tries to guess whether you want audio or not, but doesn’t always get it right. On some WebSDR sites, you’ll get an “audio start” button, on some you don’t.

If you don’t get audio, try the following:

• At the top right, click the 4 vertical dots, and then Settings.
• At the bottom, click Advanced.
• Under “Privacy and security,” click Site settings.
• Select “Sound”
• Select “Add” and enter “http://*”

^{(thanks to K9GL for these instructions)}

Note that the above effectively disables Chrome’s “autoplay” policy for all http sites.

^{Although stopping automatic sound from advertisements is a noble idea, I think Chrome’s autoplay policy is fundamentally wrong. Instead of trying to guess what the user wants, the browser should simply ask the user whether he/she wants to allow the page to play sound (and remember that for later visits, of course).}