I have some Bosch sensors. They have two windows, a large horizontal one and a small oval one. The Bosch sensor comes with the small sensor blocked by a foil faced tab. It is supposed to be pet friendly, but I can't vouch for it since we do not have any pets with which to test it.
I just recently got a Google Nest Mini (free for being a Google Fi subscriber) which I use with the Chromcast Integration app. I do have a door open announcement, but it is set to go off if the door is left open for half an hour as a reminder to shut it. The other announcements are for mode change and for alarm arming/disarming. The GNMs are a lot less expensive than Sonos devices. I have the microphone shut off as I do NOT want the device listening to me. The sound is pretty good for such a small speaker.
Unfortunately, there is no camera integration into Hubitat and I do not know if there are plans to do so. However, there are workarounds for cameras if you want to do so. My own method is to have my existing Lowe's Iris cameras (actually made by Sercomm) running and using the Motion application on Linux to record to an external hard drive. I recently changed my router to a Netgear AX3000 (model RAX40-1000NAS) router that has the capability to set up a VPN server. I did so and now I can view my cameras remotely. Do a search on the forum for Camect or go to https://camect.com. It looks like it would be good since it, like Hubitat, is local with internet access optional, but it is somewhat pricey.
A smart thermostat is very handy. When used with the Thermostat Scheduler, or with custom rules, it can adjust for home/away or day/night, or other settings to meet your needs. I have a Zen Zigbee edition thermostat and am happy with it. I had to create some custom rules for it, but since doing so, its performance has been solid. Again, search on the forum and see what others are using. There are several options.
Smart switches and/or dimmers are great for setting up motion activated lights. I went that route rather than tackle the headache of "smart bulbs." I added controllers to my ceiling fans for the lights since I was not able to lay my hands on one that could control both lights and fan. The fans don't have separate wires for lights and fan and I did not want to run a separate wire.
More contact sensors for doors and possibly windows. I have them on the house doors, the utility room door, the crawl space door, the tools shed and the yard equipment shed. I had a number of Iris 1st gen sensors and purchased some 2nd gen contact sensors. If you are going to get some, go for the 2nd gen sensors since they are Zigbee HA1.2 compliant. I had to separate out my 1st gen devices and put them on a separate hub as I was experiencing instability with them on one hub.
When it comes time to change our water heater, I would like to get one that can be integrated into the system. It is easier if the WH is electric, but ours is natural gas. It will be a while before it is needed since it was fairly new when we bought the house about 5 years ago.
Anyway, I'm sure you will get more replies with other suggestions as well. Hopefully, this will help.