Sure, although GAE is blocked in China. AWS works, and has a free tier that will get by for a year, but doesn't give you free certificates.
Also, for a lot of newbies, installing SSL certificates is a PITA.
0. You realize you need a SSL certificate. You're presented with a dizzying variety of options and already lost. Are you supposed to get Positive SSL, Negative SSL, Essential SSL, Comodo SSL, Start SSL, Wildcard SSL, EV SSL, Rapid SSL, Slow SSL, or EV SSL aux Mille Truffles et Champignons? Most newbies ask, "Why isn't there a simple [click here to get HTTPS certificate] button?"
1. You get your certificates by e-mail, but you still can't install them directly. Your webserver wants a .pem file, so you Google "How do I create a PEM file". The top 10 tutorials tell you to concatenate THREE files: your_domain_name.crt, DigiCertCA.crt, and TrustedRoot.crt in that order. What you received by e-mail was FOUR files: AddTrustExternalCARoot.crt, COMODORSAAddTrustCA.crt, COMODORSADomainValidationSecureServerCA.crt, and your_domain_name.crt. You're lost, no tutorial is helping with what to do with FOUR files instead of THREE, in what order to concatenate them, and StackOverflow bans your question. You're fed up, quit, and use HTTP. (Not me; I'm describing an actual case of observing someone else's frustration trying to set up HTTPS.)
The only way HTTPS will gain popularity is if we can get rid of the certificate-issuing economy and make it easy for newcomers. The majority of content creators unfortunately do not understand the basics of security nor can we expect them to have the patience to learn it.