Not really though. If you are building a product for a market where a portion of your targeted user base will need that feature then suddenly your MVP needs to

Not really though. If you are building a product for a market where a portion of your targeted user base will need that feature then suddenly your MVP needs to include those assessibility features from day 1 because it's part of the minimum set of features that make your product viable. For example say your startup is targeting long-term homes as a market for a new app that help residents track activities within the facilities, your app will need to be accessible as a significant portion of your user base might have trouble with technology or difficulty reading small text on a smartphone. In that situation you need to have accessibility at the top of your checklist because it's part of the minimum to make your product viable. In many ways it might even be how you displace whatever the organizers were using previously, as you beat your competition by providing a better fit for their userbase.