The requirements have been covered by others. Must have PFDs, throwable, horn, and flares (at least 3, not expired, etc).
To me it would be madness to go out without a radio, a high-quality marine compass and laminated printed map, a GPS, and a cell phone. Have a charger and / or extra batteries for the GPS and the cell phone.
The last “must have” for me at least was to have marine towing insurance. If you break down out on the Great Lakes calling a commercial tow can cost hundreds of dollars just to get you to shore. I use Boat US and for $40 a year, it’s a small price to pay for the benefits of being able to summon a tow if needed on any of the lakes.
Grouse