Custom Development (Web or App)

I am looking to build an internal daily communications chat portal. Something similar to the visual display of how iOS chat works. I am unsure if we should go the website direction or build an app for this. My boss wants it to mirror the way chat works in iOS so it is super easy for department heads to communicate efficiently.

The intent is:
Purposes: To Communicate throughout the day on a shared communications board/chat with two chat sections:

First chat segment: General Priority notes
Add a note: It should look like how it does to add a text message super simple
Note contain:
By: Department: Dept1, Dept2, Dept3,, Dept4 and Dept5
Individual Initials (ABC)
Message
Note visual: Bubble note –visually looks like text with time stamp of message
Delete option of message: only by admin, Messages automatically purge after 7 days

Second chat segment: Daily Service Notes
The only difference to how the bubble notes are broken out in this segment is this is categorized by product first then the rest of the above.
The specific product can be turned one of 3 colors – red, green, orange for status.
And the newest message would prompt the order of aircraft to move from most recent on top.

Access:
I would imagine we need invite and grant rights to the individual. The categories would need to include:
Name: First, Last Name
Department: (1-5)
Access level: Read only, read and edit, admin
Contact: email and mobile?

MAYBE, there are tools out there that can be used to customize this solution? Happy to go that route, too

What questions do you have?