What do I need to run Home Assistant in my home to devices in another building 400 ft away

Hardware
4

Yes, you likely would need a hub/bridge in your shop. Depends on the devices you would be planning to use. I can think of a couple of options:

  1. If zigbee only, there are a couple of zigbee - LAN coordinators out there. kazancsedat had an example above; zigbee2mqtt project page has a list also. The zigbee network at your shop would be a independent mesh network, but you could bring those devices back to your HA just fine. You just need to make sure the coordinator and HA can talk to each other over LAN.

If zigbee + z-wave,

  1. You can prepare a RPi plus a z-wave USB dongle plus a zigbee dongle for your shop location, and then install zwavejs2mqtt to control your z-wave…
    Quick Start (zwave-js.github.io)
    / zigbee2mqtt for your zigbee…
    Getting started | Zigbee2MQTT
    Note that you don’t necessarily need HA on this RPi.
  2. As Igor mentioned, use this integration to link multiple HA instances together.
    custom-components/remote_homeassistant: Links multiple home-assistant instances together (github.com)
    This remote HA instances would still need zigbee and/or z-wave USB dongles.
  3. Maybe get a Hubitat C-7 Hub, which has zigbee and z-wave radio, and then use this integration to bring devices from Hubitat to HA.
    Custom Component: Hubitat - Home Assistant Community (home-assistant.io)

Hope this helps.