With over 100 devices attached to my hub it can get quite unwieldy trying to manage it all. I wish there was a way in the admin interface to say group all my contacts sensors together or all my color lights, etc...
Anyone developed an app for that or something OOTB way to do this?
Assuming in the admin UI like in the "Devices" list, then I'm not aware of anything, for the most part. One thing I have seen is the Virtual Container driver, though as the name suggests, that only helps you "organize" virtual devices (by creating them as child devices of a parent "container," which of note will also give you one more device--the parent--than you'd get without it). It will not help with real devices, like a contact and motion sensor in the same room.
One thing you'll see in light of the above is careful device naming. For example, nearly all of my devices in one room start with the name of that room. For example, "Kitchen Motion" and "Kitchen Counter Lights." Something often overlooked is that you can use the search/filter box in the upper right of the device page to filter the displayed list. In my case, typing "Kitchen" (or even just a few letters) is enough to filter the list to basically just what I'm looking for, plus they're already more or less sorted that way to start. You'll also see some people do some more creative things, like starting device names with emoji for sorting purposes (apparently ignored by Alexa and other things you might care about; I'm still hesitant to do this because in the early days, staff recommended against non-ASCII characters).
If you mean for the purposes of controlling devices, then the Groups and Scenes app (mostly Groups) may be what you're looking for: you can group switches, dimmers, and bulbs together to control them via one (effectively virtual) device on Hubitat instead of doing each one individually. Cobra (and possibly others) also have apps for "averaging" or aggregating the state of multiple sensors into one device, which may be useful for displaying on a Dashboard. Zone Motion Controllers can also help to "combine" motion sensors into one device with various options for how.
You can develop a set of dashboards with your "capabilities" in it. This could provide a link to the device's edit page for detailed understanding of state.
Example: One row for each device with relevant tiles. Example below from left:
Link tile - goes to the device's edit page (link is the address of the edit page). To go back, you use the browser's return to get back to the dashboard.
Capability tile(s) - for each relevant capability, use the appropriate tile template. Can be multiple or one.
Text: Can have multiple where you place other textual information you need.
Of course, it would be cool if the HE would add a field to the device's database and page that would allow entry of a "grouping" for each device. You might ask for that feature in the feature request area of this site.
I use a combination of searching and sorting. The issue is you have to do that every time and if you edit a device and go back to the device list you lost your search and sort.
I did a quick feasibility check on my motion and contact sensors. Takes about 2 minutes per sensor once you get started (about five minutes to set up the dashboard to the way I like it. See below
Well I do that too by naming them the room and device type, but it's still nice being able to group without having to use weird names to get them to match up the way I want.