The Homey Bridge is indeed limited to the number of devices it can support. Mine collapsed around 40, which corresponds to what Homey is advising as maximum. From my understanding it needs internet to connect to your Homey (SHS) when booting, but can work without after the connection has been established. This means it can operate without internet as long as there is power and a working LAN connection.
For zigbee devices, you have the option of setting up an external zigbee coordinator, in combination with zigbee2mqtt. You would need to run the zigbee2mqtt service on your own hardware, in addition to installing the zigbee2mqtt app on Homey.
I don’t know if there is an equivalent solution for zwave devices.
You also have the option of installing a Home Assistant app on Homey. The is an official and a community version. Either of these would allow you to expose your Home Assistant devices in Homey and leverage the Homey UI for automation.
