HACS installs community integrations whereas addons are like external programs that hook in HA. You can do the same thing with HA in Docker by installing the addon containers separately and then hooking them in manually but HA OS makes it much simpler.

For example I’m running the Mosquitto broker, Z2M, a Visual Studio Code server, diyhue, and Music Assistant as addons.

Docco page about it is here: https://www.home-assistant.io/addons/

If you want to give Home Assistant a try like others are suggesting, save yourself some time and hassle and install Home Assistant OS in a virtual machine. While you absolutely can run it in Docker you lose out on some neat quality of life improvements like add ons (which, funnily enough, are Docker containers pre-configured to hook in HA).

Exactly this. Also it annoys me that Namecheap tries to automatically “top up funds” over a month before renewals are due. I think they’ve always done it but it wound me up enough this year to move to Cloudflare.