It's been great seeing game companies take accessibility seriously in the last few years. Microsoft really stepped up with their adaptive controller, and now HORI has put out an accessibility controller specifically for Switch.
The HORI Flex is an interface for Switch that allows you to connect accessibility switches, along with a handful of USB joysticks. Remapping features allow users to come up with 6 different configurations based on the buttons/joysticks they need. The device is priced at roughly $230.