Shopify recently announced that they’re working on APIs to support more than 100 variants: https://www.shopify.com/editions/summer2023?utm_campaign=Summer23Edition-Amplify&itcat=partner-dash&itterm=notification&product=product-variants
I’m assuming this will be made availabe on the Shopify Admin at some point as well, though there’s currently no timeline when it will be released or what the new limit will be.