Msx turbo-r fs-a1st motherboard versions?

That looks like a preproduction unit. There are many more changes compared to a standard A1ST, but the most interesting is the R800 IC in the bottom, on the left of the RAM. That kind of packaging is used during the development stages of new ICs.
Nice find!

What you have is extremely rare. Companies only make 5-10 units of this kind during the development process and most of them are destroyed after the product goes into real production.
So, I wouldn't do any modification to it. Maybe the conversion to 220v if you're experienced with this stuff. The memory upgrade is a lot more delicate and invasive.
Try to dump the ROMs, as they are probably unique. Here are some instructions: https://www.msx.org/forum/msx-talk/emulation/dumpingreverse-engineering-msx

There is no serial number at the back, just empty there.

That's an MSX2+ keyboard. They were there before the grey turbo R ones. So either the grey keyboards did not exist yet, or the previous owner did a swap.

I dumped the tc574000D rom chip, and according to Nyyrikki, it was same as production version.