Code Section 6428, unless it is later amended by Congress, allows the credit on 2020 returns, including final returns for a 2020 decedent,  as long as the AGI and other qualifications are met. 

According to some people's ethics, it would be wrong to advise clients otherwise.

Code Section 6428A in House bill (passed last night, awaiting surgery or death in Senate) makes qualification for another round of $1,200 payments dependent on being alive the month before enactment.  Or something like that.  Stay tuned.  

IRS FAQ's, unless published in the Internal Revenue Bulletin, do not have the force of law and can always be amended or revoked.