Regardless of the status of implementation, all websites have had to include a so-called accessibility declaration on their website since September 2020. This declaration contains legally required mandatory information about the status of the implementation of accessibility.
GP is already an accessible theme by default. However you will need to ensure that things such as the colors you use conform to those standards. Also the Theme is not responsible for the accessibility controls applied by other plugins.
If you run a test on your site and you find any issues where more than happy to take a look at provide some advice.