I'm hardly going to defend Facebook/Meta, but by and large, WhatsApp is still separate from Facebook properties. It doesn't require connecting identities to any other Meta-owned property to use it, and all messages on it are end-to-end encrypted[0] - a change which happened after Facebook acquired WhatsApp. There was a proposed change about six months or a year ago, but it was walked back after public criticism.
There are a lot of things to criticize Facebook for, but WhatsApp has remained, at least so far, pretty independent - and if anything, more privacy-preserving than it was at the time Facebook acquired it.
Of all the independent products that Facebook has degraded over time and locked in to its walled garden (Instagram, Oculus, etc.), WhatsApp is the outlier, not the rule.
[0] Every time this is brought up on HN, it always devolves into a discussion about how "the client is not open-source so you can't trust it", followed by an inevitable segue into reproducible builds and federated clients, etc. etc.