“Is Discovery canon?” is an interesting question because the only real purpose canon serves is to give us boundaries for where it’s reasonable to stop expecting (searching for?) a degree of consistency throughout all of Star Trek
When someone says “that’s not canon” what they’re usually telling you is that they don’t care to reconcile it with other Trek
Given that Discovery is two seasons of “top secret classified never happened” and three seasons of “800 years later than any other series,” even if we decided it was canon in some technical or legal sense, it gives us basically nothing that could potentially influence other Star Trek, before or since. In other words, it’s not canon in any practical or meaningful sense.
Strange New Worlds spins off from Discovery and carries on plot elements established there. Section 31 continues Georgiou’s story, and Starfleet Academy is picking up on the 31st century setting and characters. That’s a lot of ongoing influence.
I definitely loved certain aspects of discovery lol. I just hated how f’d up they made the rest of the timeline and I don’t love the future they locked TNG era into even if it was an interesting story to tell (except for the final episode with crying kid destroying dilithium because wtf)