Linux Server (raspberry pie) disk format?

Hello,

Is there a disk format that works with Mac, Linux, and Raspberry Pie?

We're trying to set up a Linux file server (via Raspberry Pie) on a hardware RAID to store all of the important files plus music, photos, movies, etc and the NextCloud alternative to icloud. The problem is that the Mac OS X 10.6 machines can not seem to recognize a RAID formatted as Ext4 which apparently the Linux Pie needs.

Since all of my computers (other than the Raspberry pie) are Macs I'm a bit worried that I won't be able to retrieve all of the data off the raid in case anything happens to the pie, especially if we create symbolic links to the itunes library and the next cloud data.

I'm currently awaiting my Linux laptop which has an indeterminate delivery date so I'm nervous about putting all of my data on a Linux only file format.

Is there any disk format that would work between Mac, Linux, and Pie?

Thanks.