I had an extension FastStream installed on all my FF and forks on my various devices (this install is on Windows 10 if it matters). But the extension got de-listed because it no longer passes whatever requirements Mozilla has for getting signed. The dev is working on getting it through, but offers it through their github via zip file. I normally use Zen, so I didn't have issues loading it and just turned off the auto update stuff that would remove it.

The old previously listed version was on my desktop that has the stable release of FF. So I removed it so I could update, but was blocked. No big deal, I went into about:config and set "xpinstall.signatures.required" to "false" per instructions. Restarted FF and now still blocked because it isn't signed.

Some searching says that stable is a no go, while other results still say to just flip that signatures.required to false. The AI assistant on DDG says that the "xpinstall.signatures.required" option isn't available on stable (even though it is and able to be flipped between "true" and "false" (I saw some people say that they see the option, but is grayed out and not able to be changed at all).

Kind of annoying that FF has been so much easier to load extensions not on the add-ons site. I have had issues trying to side-load on Chromium browsers I use, and FF never gave me this problem. I imagine it will eventually be an issue for the Bypass Paywalls Clean extension (not sure if extensions not listed on the site can get signed).

Is there any simple way to force it on stable? If not, can I simply "upgrade" my stable to beta or dev, keep my profile, and remove stable without losing anything? Would like to avoid ESR since I do like to know when features/UI changes happen so I can help people (I work on consumer PCs) that use stable on their devices.

Thanks in advance for any guidance!