One thing I would suggest is buy a Home Assistant Green now and start integrating what you already have. It is a steep learning curve with HA to get the polished look you see in many dashboards.
As many have said it will evolve with you. Pick a project to integrate into HA i.e. your cameras, then make a dashboard to display them how you want.
You will need a decent Wifi and Zigbee backbone. Consider where you may want POE devices like Access Points, Zigbee Repeaters, Displays and Media Players. For POE you will require ethernet. I can highly recommend Unifi for ethernet network and the access points will handle multiple hundreds of devices connected, unlike a lot of consumer grade or ISP provided routers. A Unifi UDR is all you may need.
Wire all your switch plates to have a neutral wire, to increase compatibility with smart switches available.
Example below of Unifi deployment.
Example below of dashboard hardware.
The bible is the Home Assistant Cookbook.
Read my HA journey in my profile blurb. You will get it to a point where it is largely set and forget but will be forever tweaking, fixing things that break and finding new things to install.