The question I'd have is what is the driving force behind the initiative to move to Functions? If the answer is "reduce infrastructure costs", I'd ask serious questions if the "juice is worth the squeeze" for a transition, and then create estimates for the cost of transition versus cost savings. For a 100 user app it is likely not going to have much payoff unless your infrastructure bill is a lot higher than I expected ($10-12k).
However, if the answer is "to create a better integration architecture between our apps and services" then you should engage with that. Azure Functions pushes developers really hard toward creating APIs that are discoverable and reusable, especially in a Microsoft oriented enterprise where you start seeing other tools like logic apps or the power platform start being able to produce and consume for custom functions. Over time, I've watched benefits accrue from common integration points functions drive across the organization.
So, ask questions, but make sure you understand what the organization is trying to achieve with the recommendation.
Disclaimer- I'm a Microsoft employee, but opinions my own.