Installing macOS on an external drive

[Adenitz]

Hello guys,
i have read this article: https://www.howtogeek.com/293476/how-to-install-and-use-macos-sierra-on-an-external-drive/

It gives pretty good and straight forward explanations.
I have MBA early 2015 with Big Sur. I want to install High Sierra on Transcend Jet drive with USB 3.0 interface. I know how to do this from Big Sur.
I already have JetDrive 520, which I can use as an external backup drive. Now, I want to format it and install High Sierra on it.
I can use this external drive on other laptops for testing purpose. Now, since inside this Jet pack there is a PCIe SATA drive, I wonder if it is possible later, just to open the case and swap it with my original SSD drive?
Will that work, or I need to install High Sierra again?

Thank you.

 

[appltech]

In theory, it should work.
However, I don't see JetDrive 520 model listed as compatible with your MBA model.
Double-check it at https://www.transcend-info.com/Products/No-625 (closer to the bottom of the page).

 

[NoBoMac]

Don't think this will work, as those Macs have a proprietary connector.

MacBook Air 11" Early 2015 SSD Replacement

Use this guide to upgrade or replace the solid-state drive in a MacBook Air 11” Early 2015. This MacBook Air uses a proprietary storage drive...

www.ifixit.com

This MacBook Air uses a proprietary storage drive connector, and is therefore not compatible with common M.2 drives without the use of an adapter.

Seem to recall discussion in the past around trying to upgrade these, just don't recall if anyone found/recommended an adaptor.

 

[Apple_Robert]

You need to find an Apple OEM SSD. Otherwise, you may have connection problem not to mention a potential battery drain problem and TRIM problem that would require a third party app. Apple OEM SSD can be found on eBay at a decent price.

I have the same MacBook Air (recently purchased) and plan on upgrading the SSD at some point.