X went back on that quite some time ago. Have a bird post: https://x.com/GuGi263/status/2002306730609287628

(You won't be able to read replies, or browse to the user's post feed, but you can at least see individual tweets. I still wrap links with s/x/fxtwitter/ though since it tends to be a better preview in e.g. discord.)

For bluesky, it seems to be a user choice thing, and a step between full-public and only-followers.