The ATVO (public transport company of the Region Veneto) offers transfers from Marco Polo Venice Ariport and from the Treviso Airport to Venice and back – and has adapted vehicles for people with different disabilities, included those who use an electric wheelchair or scooter.
You need to book the pick up so they can bring the right vehicle but the great news is that being a public service, it has very reasonable prices. Also, if you ask for a pick up at the airport, the staff of the bus will take care of you and help with your luggage also. They are super nice and will ensure that you reach your destination safely.
Visit their website to book and specify your needs when booking, using the contacts form.