I guess it depends on what you consider "canon". I'm typically in favour of letting viewers decide on a 'personal canon' rather than a 'prescribed canon' anyway tbh, but let's look at it this way: It was already clear from AoS itself before the Loki show came out that AoS at least diverged from the 'main' timeline at some point. This would presumably be due to the timetravel in late season 5. But does that make it not-canon? Because this Loki is divergent from the 'main timeline' too, so would that make Loki not-canon? I'd say AoS is about as canon to the MCU as things like Age of Apocalypse, Age of Ultron, etc. are to the main comics line. That is, it is a divergent timeline that originates directly from the main timeline.