Which board/shield to generate (non-PWM) analog outputs?
For 12-bit dual DAC you want the MCP4822 which has two channels of 0-4.095V in 1mV steps.

The output of that you would then need to pass through a suitable amplifier arrangement with an op-amp giving a gain of 5 and adding an offset of -10V.  The gain would change the 0-4.095V to 0-20.475V, and the -10V offset would change that to -10V to +10.475V.  If you want to get more precise you could use an offset of -10.2375V (it's not easy to make an offset voltage that precise) then you would get -10.2375V to 10.2375V in 12-bit resolution.

It's doubtful you'll find a board already made up with that specific arrangement (it's fairly specialised) but it's not something that's hard to make - all the components are available as DIP or other through hole components, and the circuit for the amplification stage is pretty simple (check for non-inverting op-amp circuits online, there's millions), so building it up on strip board or matrix board would be easy enough.