Using External Hard Drive to transfer files from MacBook Air Early 2015 to a MacBook Air 2024

Almost any USB drive should work. You will just need one that has both USB-A and USB-C connectors (via cables or cable adapters).

OWC has a nice external SSD drive that looks like a flash drive and it has both types of USB connectors built in.

250GB OWC Envoy Pro mini

Whatever drive you get, format it as MacOS Extended (Journaled) on your old MBAir - that way, it can be used with both of your MacBook Air laptops.

Note that you can upgrade an Early 2015 MacBook Air as far as Monterey. Monterey soon will drop out of "the most recent three," but if you wanted, you could

• Back up your old MacBook Air
• Upgrade it to Monterey – either directly, or in stages (Sierra -> Mojave -> Monterey)
• Sort out the effects of that upgrade (e.g., the loss of 32-bit applications)
• Make another backup of your old MacBook Air, and do the migration to the new one from that

This would make individual upgrades a bit more incremental, instead of going from (Intel + Sierra) to (Apple Silicon + Sonoma) all at once. You don't need to do it – I'm just offering it up as a thought.

How to download and install macOS - Apple Support

Servant of Cats wrote:

Note that you can upgrade an Early 2015 MacBook Air as far as Monterey. Monterey soon will drop out of "the most recent three," but if you wanted, you could

Certainly a possibility but one that requires considerable work and carries the risk of untoward things happening and/or being migrated, especially in a jump like from Sierra all the way to Monterey ... and from Intel to Apple Silicon.

Just today there was a post from another OP who migrated from an older Mac and wound up unable to install his Epson printer on his new Mac. Turned out the problem was deeply obscure - a migrated .kext file that was corrupted during the transfer. You can never really know everything that gets migrated, which is why I do not advocate migrating from one Mac to another; and definitely not from Intel to Apple Silicon.