qosmio's NSS builds use the same hardware definitions and code changes created by lytr and asd111333 for this new hardware model MX4300. On top of these changes, qosmio added NSS firmware/driver patches, some newer ath11k firmware/driver etc.
Since lytr's PR has not been merged to the OpenWrt main branch, there is no official main SNAPSHOT for this model MX4300. You have to use community-built images (NSS or non-NSS) or build them yourself.
If your WAN speed is less than 700-800 Mbps D/U, there may not be much advantage to using NSS images since software offloading (in non-NSS images) may still help achieve such speeds for WIFI.
Since ath11k firmware/driver may not be as reliable as ath10k ones, some people reported random WIFI problem with either NSS or non-NSS images, depending on their environment/WIFI clients. Just try both images and use the one with the best WIFI results for your environment/WIFI clients.
Last but not least, you will not save any electricity by using NSS images despite apparently lower CPU utilizations. As a matter of fact, NSS images will use a bit more due to the activation of the NSS cores.