First, Control 4 is on a very different level, so comparison isn't that easy. However, you can have a far less expensive and very capable system with Hubitat, but you're going to need to do all the work and handle all the support, vs the Control 4 dealer doing it for you.
A lot of choices in recessed lighting available. I would personally steer toward fixtures that could take G10 or E26 bases. That way you have the flexibility to use smart bulbs and that makes customizing zones very easy.
Nest- Yes
Ring - Not yet
Simultaneous doorbell and lock, not certain what is meant by this question. Certain locks are supported at this time. Video doorbells, not yet, but maybe Nest Doorbell [needs citation]
Shades - Lutron Serena
You'll be able to setup Lutron integration with Hubitat to do exactly what you're asking.
Here's a user maintained Compatible Devices Wiki
It's a bit out of date I notice, so here are the devices and apps that are integrated with Hubitat to date. Add to that the hundreds of user created apps and devices, you've got quite an extensive offering here.
Built-in Device Drivers
Built-In apps
