Timmy, Tommy, stop following me

You need at least 30 days of play

Nope, selling hot items doesn't seem to have worked either.
Seems like the only thing left is either selling turnips or just waiting for some random chance thing to happen.

I've bought and sold over 500k bells worth of goods, have 2 bridges and inclines, and been playing since it came out, still no upgrade
The two things I haven't yet done are sell more than 2 hot items or sell any turnips.
So I just sold 28 hot items and I'll p.ost tomorrow if that unlocks it.

Some people are speculating its just 28 days after unlocking it

I've sold over 500,000 worth of stuff and have bought over 100,000 worth of stuff and have still not gotten a request to upgrade.

The 100,000 sell requirement is definetly wrong. Have over 1m bells from selling sharks and scorpions and I still have nooks cranny

your should replace "cherry" in your list with "your native fruit"