Follow the instructions
here.
To make it automatically boot the 1st entry of CFW Atmosphere change the following setting in step #2:
You will need to create a second entry for SXOS. To boot to the second entry you will need to interrupt Hekate when it’s booting by pressing (
volume -) and selecting the appropriate entry.
I personally have a 8G resized file based emmunand on FAT32. It’s a little risky due to potential file system corruption but I only mount XCIs in SXOS. The recommended approach is to use two hidden portions to avoid corruption as detailed
here.
Im on a V1 Erista so the only thing I’m not 100% sure about Is doing this on a Mariko But there are folks that say it worked in the thread above so you might want to chime in there.
There are tons of threads about this. I highly recommend you read, read, read everything you can if you’re going to be running more complex setups because you will have to take it into account when you upgrade or make any other changes to your system in the future.
Good luck!