are there any news about the RevPi based on a Raspberry 4b? Further i would like to ask if there is a possibility to upgrade the RAM on a RevPi 3 ?
Since the RevPi is based on the Raspberry Pi Compute Module, we can only wait til the Raspi Foundation releases the Raspi 4 as a compute module version.
Unfortunatly the Foundation ain't giving much information about if they are planning to do so and when they plan to release it.
There is also a thread on the official Raspi forum about this:
https://www.raspberrypi.org/forums/view ... 5&start=25
Regarding your second question: RAM upgrade is not possible. Sorry.