FM-Pack cartridge for my MSX2 Philips NMS8280

Just be sure to have a couple of different CF cards. Not all work. Not sure anymore which one it was, but it was on the QFL of the manufacturer, just a bit older or newer. Same brand same size. It refused to work. I do believe the manufacturer's claim that the exact cards on the QFL will work.

I would recommend the C2, I acquired one used. You can use the built in control panel to adjust volume controls, PSG, SCC, and FM-PAC, and additional banked RAM.

You can load ROM images into the flash memory of the C2, which are shown as a menu on the boot screen

You have FAT16 (2Gb Maximum) built in using the Nextor operating system, you will find SofaRun the most useful program for running ROM and DSK files, if you have a card larger than 2Gb it will partition into multiple partitions.

I have not used it with your model of MSX, but it worked well with a Sony HB9F, Toshiba HX10, and my Sony HBFX1DJ. I confess I have both the MFRSCC+SD as well as the C2, my favourite is the C2, the only reason I keep the MFRSCC is so that I can use games that use dual SCC.

I am unsure of the SCC implementation, the C2 is a very different device, with its flashROM menu that can be filled with ROM images, as well as the FMPAC.

The Carnivore2 read the file .CAS??

I think you should have a read here (copy/paste the complete link up until the page=7 part):

https://raw.githubusercontent.com/RBSC/Carnivore2/master/Doc/Carnivore2%20User%20Guide%20(English).pdf#page=7

If, after reading, there's still something you do not understand, there's always someone to help you.