Why don’t wireless connections (WiFi, Bluetooth, etc.) use anything between 2.4Ghz and 5Ghz?

The reason 6Ghz was introduced with WiFi 6E and 7 was because 2.4Ghz and 5Ghz was very busy.

My question is why isn’t there anything in between? Why isn’t there a 3Ghz, 3.5Ghz, 4Ghz, etc?

Also, what if things that require very little data transmission used something lower than 2.4Ghz for longer range? (1Ghz or something?)