Excel formula-based function for SHA256 / SHA512 hashing without VBA or macros

Question

It's the year 2017 and anybody who needs to use hashes should avoid 'broken' ones such as MD5, if security is important. Has anybody found or created a way to do more secure SHA256 or SHA512 hashing in Excel, without using VBA or macros?

A spectacular example of this being done before was over 3½ years ago with MD5 (as seen in this SO: MD5 Hash function in excel without using VBA).

Reason for avoiding VBA/Macros: Compatibility with mobile devices, such as Excel for iOS.

Side Note: The original Stack Overflow post has a successful answer with a dead link, here is a new link for reference: https://tzamtzis.gr/2017/web-analytics/excel-function-md5-hashing-without-vba/