You are missing the point. Sigma is offering a LEGO piece that one can use to assemble one's own configuration. Viewfinder and everything else can be added.

They also offer two other sensor LEGOs: one that looks like a previous/heaper gen (fp) and other with high-res 60+ MP sensor ("fp L").

I like the idea.

You are missing the point.

None of that can be added. It's not an fp. It doesn't even have a hotshot and there's no EVF nor 'everything else' as add-on.

Only changeable things are L-mount lens and battery

>everything else can be added

except an SD card

IMHO SD cards fail much more often than the USB-C connector would, what's the worry? If the camera mounts as a mass storage device it's one fewer thing to go wrong.

Firstly the main failure of connectors in cameras isn't the connector per se, it's generally the board that the connector is mounted on breaks off from the mainboard.

Secondly, and more importantly, the lifespan of your camera is now the lifespan of the internal storage. That seems very unappealing.

Doesn't really bother me. 256GB isnt the lap of luxury but it's not bad, is what I'd bring on most trips.

If you can backup from the camera to SSD, that's a much much much more tempting option anyways. Anyone shooting video is already used to having a Samsung T7 SSD strapped somewhere to their rig. SD is handy as heck & so good to have but vastly fantastically slower & not as reliable.