Long time ago I was thinking about using these ST Arrival sensors. When I finally decide to try them they simply disappeared and became not available to buy them. So, I decided to use BLE Beacons. These toys worked very well but unfortunately the security of BLE Beacons is zero. next step was to use Active RFIDs. This is current working very well implementation. However this conversation inspired me to create one more (I am already using few) DIY Hubduino project which will replaced multiple currently used devices. The devices are:
Dual Zigbee Relay to control Door Actuator;
Zigbee Door Sensor;
Zigbee RGB Controller for controlling LED Door Activity Status Bar;
All the above could be replaced with a single DIY Hubduino Controller. In addition I will add a Reader for the RFID Tags. These are already used for entering into a building and recently added for using elevators. This way my original idea to automate apartment door for 100% hands free operation is effectively broken. So adding RFID Reader, compatible with existing RFID Tag at this time is a very good idea.
I know you're not looking to use this for security like locks, but what if you did? It occured to me that a lock like the Aqara U100 allows entry by passive RFID tags (two included), Fingerprint, Apple Key, Code, and as a backup, a regular key. If you can get status from any one of those, then a simple Rule Machine rule can combine the unlocked by [person] status followed by motion inside to indicate you're home. Can do similar for you've departed. This could be done with many other door locks too, because Hubitat can know which lock code was entered via status from Lock Code Manager.
Another possibility is the SwitchBot contact sensor. I have several of these, and although I don't use them for presence, they are designed to do just that. They have a built-in motion sensor and can sense motion detected, then door opened, then closed=you're gone. Conversely, door opened, then motion=you're home. There's a community integration for their hub, and they also have Matter support for their hub which is in development for HE.
Related to this piece, though not geared at Presence per se, my app Contained Motion does something similar with Contact and Motion -- given a space where all exits have contact sensors, if motion has ever been active inside it, someone must still be present until an entry/exit opens.
One could do that for the entire house pretty easily, though it's geared for individual rooms.
This is exactly how my presence detection rm rule works. The trigger is apartment door is closed. Then rule checks multiple motion sensors for inactive state with 15min timeout whichever happens first. If all ms inactive then nobody at home. Otherwise somebody still in apartment.
These ones just arrived today, in original packaging (albeit the packaging isn't in great shape), for $15 each at the link above. Previously, I've paid up to $40 for ones that came refurbished in an unmarked envelope.