This is strange, but I just saw that if you have an amazon prime account, you get "grubhub+" free with it... and can apparently order through amazon
https://www.aboutamazon.com/news/retail/amazon-prime-grubhub?tag=associatessrp-20included with their Prime membership on an ongoing basis, so no automatic renewal into a paid Grubhub+ membership will be required. Grubhub+ includes $0 delivery fees on eligible orders over $12, lower service fees, 5% credit back on pick-up orders, and exclusive offers.
Amazon customers can now access Grubhub conveniently on Amazon.com and in the Amazon Shopping app, enabling them to order Grubhub while shopping on Amazon without having to download or switch to the Grubhub app. Visit amazon.com/grubhub to complete a food delivery order with Grubhub.