personally I feel that you can consider making the snackbar floating above the CTAs on the bottom of the screen. You would still have to consider the overall flow and feel of the screen so that the snack bar does not feel irritating to the user.
Not sure how your CTAs look like, please share some diagrams if you like to exchange ideas on the snackbar ...
Personally I have started preferring bottom nav bars as screen sizes for mobile phones tend to increase.
This is helpful for instant navigation and doesn't tire the user if he is using the app too much.
That certainly depends on the how the information architecture is - categorization of information hierarchy.
Bottom Navigation is mainly used to navigate between primary destinations in the app. From the above example, the primary navigational tasks - which the user will most often make - is to move between home, messages, and info.
Bottom App bar, however, ...
Well, there is a section about exactly this topic in the Material Guidelines:
Combining bottom navigation and tabs may cause confusion, as their relationship to the content may be unclear. Tabs share a common subject, whereas bottom navigation destinations are top-level and disconnected from each other.
Basically it's simply about confusion. If you ...