No. Those are small boats that require going down a couple of stairs.
From WDWinfo (above)
Gold Flag Launch: The gold route carries guests from the Magic Kingdom to Disney's Grand Floridian Resort & Spa, continues to Disney's Polynesian resort, and back to the Magic Kingdom. This route goes in reverse of the resort monorail. This route operates 30 minutes before park opening including Extra Magic Hours until 1.5 hours after park close and typically has two launches on the route. This route can not accommodate ECVs. Guests in Wheelchairs can board if they can transfer out of the wheelchair and step down 2 feet into the boat. Travel time on this route is about 20 minutes around the lake, so it's about 7 minutes between stops. Wait time between boats is typically 10-15 minutes.
You might be able to leave it where you can rent ECV in the park, but there is no place outside the park to leave it safely. If you want to take a boat ride, you could use the ferry from MK to TTC and then scoot/walk to Poly and/or GF.