You should make every effort to claim your Google My Business listing. If your listing is unverified, you have no way to add photos, posts or optimize your listing. Your listing will eventually risk having an outdated phone number, address, or name. In competitive markets, optimizing your Google My Business listing is a baseline requirement.
You are going to want to incorporate ongoing posts, photos and reviews as part of your SEO strategy. None of these things are possible without claiming your GMB listing first. Go to https://support.google.com/business/answer/2911778?co=GENIE.Platform%3DDesktop&hl=en right away if you have a business that is not yet claimed.