I tried this myself, but it’s hard for a few reasons:

• Messaging actually takes more time (defeats some of the purpose)
• No banking apps (inconvenient)
• No proprietary 2FA (nonstarter for work reasons)
• No “let me Google that real quick” moments (comparison shopping when in store, looking up a phone number for a restaurant, etc.).
• Their cameras universally suck

Some “dumb” phones still have a web browser and such, so you’re not completely out of luck, but it’s painful.