Paypal checkout is possible, there is no real integration but you can generate an embed code within PayPal that you can embed on your Fastpages page. If you have a Paypal account you can go to your settings and go to "Merchant Services". How to set up the button within PayPal differs per country, therefore it's best to reach out to their own helpdesk articles. This is the article you need: https://www.paypal.com/us/smarthelp/article/how-do-i-add-a-paypal-payment-button-to-my-website-faq3629
Once you have made the embed code you get a code snippet, just use the Embed element function to put this snippet on your page and you are ready to go.
