Hi David,
As you say, without more detail on the severity of the visual impairment, it’s impossible to know what might work, but clearly the more light the better…so, a large aperture telescope pointed at the Moon would surely stand the greatest chance of success….Alternatively >Are there any other facilities that a near-blind child might use to get a sense of the planets?< There is this chap, Nic Bonne at Portsmouth Uni, who may (Covid restrictions permitting) be able to offer advice…..
https://www.bbc.co.uk/news/av/uk-england-hampshire-51559823
Martin