In my opinion zen'os attack only destroid all mass and all forms of life (including abstract entities) in this universe. Reason for this is that goku was able to go to that place in after zeno did his thing. Goku would not have been able to go and survive in a place in which the universe itself (spacetime) was destroyed or like you said eradicated.
Also the thing with yuno dying and the universe falling appart, this is powerscaled from deus ex machina. When he died exactly that happened, some sort of black holes started erasing everything leaving nothing but a void (if it affected only matter and stuff or spacetime itself I don't know anymore). Though admittedly it takes far longer to take effect compared to zen'os attack.
About the nigh-omniscience it's listed under abilities for what reason ever (same for nigh-omnipresent), (more details
[1] ). I did this powerscaling because yuno became the next god after deus ex, taking over his powers as well as his title of god of time, space and causality.
A feat I can remember is that in the end yuno and yukki recreate a universe that has become destroyed after deus ex died.
I will rewatch certain scenes from both dbs and mirai nikki when I have time, then I can give more accurate descriptions.
Btw. I can't remember zamasu doing any reality warping aside from becoming an abstract entity, did I forget something? Besides I don't think he would be able to overwrite the power of a god governing causality and space-time, if he could I doubt he would have gotten stomped so hard by zen'o.