Is Firefox browser a known developer to Apple?

That has nothing to do with Apple. What you are showing from Firefox is that to install Firefox, you drag the item labeled "Firefox" to your Applications folder. Then double click on Firefox from that Applications folder and the program will start up and will complete the installation.

SSL-ADT wrote:

• My MacBook Pro settings mentions the following:

Allow applications from: App Store and known developers

That has to do with whether an application is digitally signed.

Signing Mac Software with Developer ID - Apple Developer

"Gatekeeper on macOS helps protect users from downloading and installing malicious software by checking for a Developer ID certificate from apps distributed outside the Mac App Store. Make sure to sign any apps, plug-ins, or installer packages that you distribute to let Gatekeeper know they’re safe to install. You can also give people even more confidence in your apps running on macOS Mojave or later by submitting them to Apple to be notarized."

It has nothing to do with whether installation is "drag and drop" (as in the case of Firefox), or whether it involves an installer. (Other than that, if there is an installer, you'd want both the installer application and the application that it is installing to be signed and optionally notarized.)

I don't get it? What is the issue.

Grab a hold of that install Firefox icon and drag and drop onto that alias of your Applications folders.

It suppose to make it an easy GUI.

FireFox has been my main working browser for over a decade. I do leave Safari set as the default.

I always have the two browser running...

You need to drag the FireFox icon to the Folder to install it.

Is there an issue when you attempt to drag the Firefox icon to the Applications folder as indicated?

TT123B wrote:

I thought developers were not allowed on this

This was not a developer-related question, and not related to code-signing or to developer ID or such.

Developers are most definitely active on this forum, though technical questions from developers are rather rare around here, given the availability of the developer forums and developer technical services.

Various developers are replying to questions around here. There are developers with level 10 around here, too.

This particular question involved a particular and old Mac app installation idiom, one not very well documented, and one that can be confusing when first encountered. (This installer idiom certainly confused me, back when I first met it an aeon or three ago.)

For the person installing the app, most installers will have some instructions available about how the installer works, separately snd sometimes also directly in the DMG. Here is the Firefox DMG installer documentation:

https://support.mozilla.org/en-US/kb/how-download-and-install-firefox-mac

There are tools available for developers to more easily build and verify these DMG installers too, including DropDMG:

This is a really old-style installer. Many years ago, all installers looked like this. Although normally, they would have added a background image that included text telling you what to do.

In keeping with modern aesthetics, they've removed the text and replaced it with a gradient squiggle arrow.

They do have some instructions on the web site too, where it says:

Having trouble? Get help with your installation.

I wonder if they wonder why they're losing browser share when they're only appealing to the old timers who still remember this stuff.

TT123B wrote:

I thought developers were not allowed on this

Apple has separate forums for development questions. But there is no rule saying that people who are, or were, software developers, are not allowed to post here.

Note that the OP's question was not about how to develop software, but how to install it. The OP's first guess – which turned out to be incorrect – was that the software in question was unsigned.

SSL-ADT wrote:

Very smart...

is your issue resolved or you still have a problem...? This is not clear from your followup post.

I thought developers were not allowed on this

SSL-ADT wrote:

Okay, it was a guessing game and you figured it out. Good work!

It's good to hear that someone advanced up the evolutionary chain.