Are you sure? Everything I've seen and dealt with, is that it is taxable, because it was only given as a result of CARES (disaster declaration is the why, already, so there is not also declaration exemption) and it is supposed to be spent as usual on mitigating the impact of the declaration. That means the reportable income is going to be offset by reportable but unexpected expense.

I have had this tab open for nearly a year:

https://commerce.mt.gov/Montana-Coronavirus-Relief/Awarded-Grants

And they give me this link:

https://www.irs.gov/newsroom/cares-act-coronavirus-relief-fund-frequently-asked-questions