I transferred from my MacBook 2011 to MacBook Air 2020 using the preinstalled migration assistant software. It took like 6 hours, but neither computer got warm or had fans spin. If you transfer this way, I recommend that you connect via Ethernet cable. I was doing it through wifi, and a message on the screen said ethernet would have been faster.
If you transfer via Ethernet, your new computer will need an Ethernet adapter because the 2020 MacBook Air does not come with an Ethernet port. I had a regular MacBook, not an air, so check the ports on your computer. You may need an Ethernet adapter for both computers.
The 2020 Air will need a USB-C to USB adapter too because it only comes with USB-C ports.
my MacBook was running Sierra while my new computer was running Catalina.
Although it took a long time, it was well worth it. I have my apps the way I want them (set up like they were with Snow Leopard — apps in an app folder on the dock instead of in Launchpad). I had to go through all my apps on my new computer and update them after they were transferred to the new computer. I knew the 32 bit apps wouldn’t work on the new computer. I had to look to see if 64 bit versions were available. Some are still waiting for update to be released. If I want to use those apps, I will have to use my old computer for those.
