When will Big Sur OS be available to install off bootable media?

From directions here (https://www.macworld.com/article/3566910/how-to-create-a-bootable-macos-big-sur-installer-drive.html):

Use the Terminal to make a bootable macOS Big Sur installer drive

You’re going to use the Terminal to make your external drive a bootable macOS Big Sur installer. Don’t worry if you’ve never used Terminal before, it’s easy. Here are the instructions.

1. Connect the external drive to your Mac. In these instructions, I use Untitled as the name of the external drive. If your drive is named something else, you need to change Untitled to the name of your drive.

2. Launch Terminal (/Applications/Utilities/Terminal.app).

3. Select and copy the following:

sudo /Applications/Install\ macOS\ Big\ Sur.app/Contents/Resources/createinstallmedia --volume /Volumes/Untitled -- /Applications/Install\ macOS\ Big\ Sur.app

4. Go back to Terminal and paste the copied code at the prompt. Remember to change Untitled to the name of your drive. Press Return.

5. Terminal may ask for your password. Enter it and press Return.

6. Terminal will warn you that your external drive needs to be erased. To proceed, type Y at the prompt and press Return.

7. An alert may appear asking for permission for Terminal to access a removable drive. Click OK.

8. You’ll see that Terminal erases your drive and then copies the installer file to your drive. This will take a few minutes.

7. After copying, Terminal is done. You should see Terminal display a message saying your drive is ready for use.

This worked for me. Hope it helps you!

Have a look at this article;

https://www.macworld.com/article/3566910/how-to-create-a-bootable-macos-big-sur-installer-drive.html

DonB58 wrote:

Hello

I was going to install the Big Sur OS, but I don't have enough space even with uninstalling all the 3rd party apps and Apple extras like pages, etc.. My Mac Mini 2018 has the base configuration for the main drive 128 GB. With the dump of the apps mentioned above the install is still asking for 15 GB of space. I figured I could solve the issue by placing the Big Sur update on an external drive. It didn't work as I read you need to create a bootable media, but currently that is only available for beta candidates. Sio as this post's title states, " When will Big Sur OS be available to install off bootable media?" Anyone in the community heard about this issue with others who have the small drive?

https://bombich.com/blog

That’s right. You’d be using the external just to hold the installation files. The OS itself will go to your existing drive if you instruct it to during the installation procedure.

Good luck!