Firefox 153 (still in beta, to be released July 21th) will ship DevTool's "Local Mode", allowing you to very easily load files from local folders using custom origins.
So you can use have https (and use all APIs requiring Secure Contexts, like Wasm, Service workers). And have custom storage per folder for cookies and LocalStorage.

Documentation: https://firefox-source-docs.mozilla.org/devtools-user/local_mode/index.html
(also have a look at screenshot's alt-text)