Google Search Console might have recently suggested you add a sitemap to your website, but your B12 website doesn't need it!
Sitemap files are useful when you have hundreds of pages that search engines can't find on their own by crawling your website. For a small business website, especially one that's built for SEO like your B12 website, search engines can easily find all of the pages on your website.
Google Search Console also has a bunch of other rich functionality that you can use despite not submitting the sitemap. In particular, if you click on the "Coverage" area on the left bar, you will see a list of all of the pages Google has found on your website. You should see all of your website's pages listed as valid. If you don't, let us know and we will investigate further.
Once you've confirmed that you've got good coverage in Google, you can use the "URL inspection" area to search for individual page URLs, or the "Performance" area to see how many times your website shows up in search results ("impressions") or receives clicks ("clicks").
If you have any questions, email us at email@example.com