anylinuxfs

Mounting 3rd-party filesystems on macOS has always been tricky. There's official support for reading NTFS but otherwise we've mainly used solutions based on macFUSE. We've got NTFS-3g which is a pretty mature driver but for Linux filesystems there's only a couple of experimental solutions like fuse-ext2 or ext4fuse.

If you want a reliable solution with write access, you need to run a Linux virtual machine with physical disk access and take care of exposing the mounted filesystem to the host. This is exactly what anylinuxfs does and it streamlines it so that it's as easy as running one command in terminal.

You pick a drive, mount it with anylinuxfs and it appears as a NFS share on localhost. This spins up a microVM in the background which uses the real linux drivers, so you can access anything from ext* to btrfs. Any mount options on the command-line will be forwarded to the linux mount command, so you can mount read-only, read-write, pick btrfs subvolumes, etc. Then you simply eject the drive in Finder or use umount in terminal and the virtual machine will be turned off.

This all sounds like a lot of work but it's actually very fast. Not like a traditional virtual machine which takes a while to boot. This one is just a stripped down version of Linux, there's not even a UEFI firmware. Practically, it takes only a couple of seconds before the drive is mounted and ready to use.