I was going to mention this but glad I found it. Great extension for Safari. One of the greatest things about this is you can change the options per website. So if you use something like Notion you can use their shortcuts just for their website and the default browser ones for everything else.
I use both safari and chrome (and dabble in FF), and in my safari usage I haven't actually come across sites that disable paste. I kind of assumed this was built-in to safari, but I may just be getting lucky.
But the best feature of StopTheMadness is that it defeats the google link tracking! I've so missed that feature of whatever chrome extension I was using.
https://underpassapp.com/StopTheMadness/