Yes. Most ZLL devices will join a ZHA network and “fall back” to that profile. The difference is really in the commissioning process and node communication layer, with some enhancements to the actual commands/attributes; but it’s built on top of ZHA. Upcoming Zigbee Pro will consolidate these into one, so it has better interoperability like zwave.
Hue bulbs do not have an easy method to factory reset them (most zigbee bulbs can be reset by physically powering them on & off in succession), so they need a ZLL controller to reset them. Since ST is ZHA, it’s possible that they get stuck on your ST zigbee network with no way to remove/reset. This concern has been alleviated somewhat by the new Lutron Connected Bulb Remote, which can initiate this reset even for ST connected bulbs on a non-ZLL channel.
Still, the bulbs will have better overall performance using the Hue Hub especially for controlling groups and scenes. There is also robust 3rd party apps to do things like sync your bulbs to music. This is because the Hue Hub is ZLL and zigbee only, so it makes use of the full power of zigbee including groups and scenes. It’s just a tighter integration.
Here’s a whole thread dedicated to the discussion of direct connecting…Personally, I wouldn’t recommend it unless you are pretty technical and really understand the tradeoffs. The Hue product is by far (IMO) the best performing lighting system in the HA space.