I'm looking for the latest (circa 2021), recommended, standard way to store a file locally in the browser for a particular user and domain. By "Standard" I mean some API that is supported by at least Chrome and Firefox now, and is either part of the W3C or Living Standard, or at least has some good indications that it will not be deprecated in the next 5 years.

There seem to be multiple "old ways" that seem to fit what I'm looking for:

• LocalFileSystem was never widely adopted and now deprecated
• File API: Directories and System "defines a means by which a user agent may expose sandboxed sections of a user's local filesystem to web applications" but is deprecated/discontinued. (The underlying File API is not.)
• "File and Directory Entries API" (aka. "FileSystem") seems promising (as of this writing, the article on MDN was last updated in Aug 2021), but...
  • The spec says "It is not a W3C Standard nor is it on the W3C Standards Track"
  • Spec also says it was "initially implemented in Google Chrome. Other browsers (at this time: Edge, Firefox and Safari) are starting to support subsets of Chrome’s APIs and behavior. The intent of this document is to specify the common subset to ensure that the implementations are interoperable." (Sounds like they are just plugging a hole in interoperability, and not trying to define something for the future.)
  • Chrome (v93) seemingly has no way to inspect these files in the Developer Tools, which could be taken as a sign that it will be deprecated

There are the more standard storage methods, but neither is focused on saving files:

• Web storage (localStorage and sessionStorage) is part of the Living Standard
• IndexedDB is on track to be a W3C recommendation

Am I missing an option? Is there a more standard web file API for the near future (2021 and beyond)? Should we just be using IndexedDB? (Bonus points if the file API also works in Cordova, since the popular file plugin uses a weird mash up of the deprecated File API and LocalFileSystem.)