It wasn't inspired but thanks for the link! If I had known of the device notification integration, I would have just used that instead of trying to roll my own logic :D
You also can take a lot of it out of the manual config by creating an input_select with various options to track the operational state of the dryer (Off, Drying, Finished), then use traditional automations to trigger switches between opstates and notifications based on opstate change. There are many threads on the HA forums and community about how to do this.