Not all browsers have an "Open in" service. I tend to use Chromium for media so it's a different crashy app than my main Safari. I've been manually copying URLs, pasting into it.
Open Automator, create a new Quick Action, pick Run Shell Script, paste in:
read -r url
open -a Chromium "$url"
Save it as "Open URL in Chromium". Quit Automator.
You can now right-click on any URL, Services menu, and send it there.