I’ve read that if you ultimately receive a PPP loan or refinance an EIDL into a PPP loan, any advance amount received under the Emergency Economic Injury Grant Program (i.e., $10K EIDL advance) would be subtracted from the amount forgiven in the PPP. Is that your understanding?

Yes.  I read the code and that’s how it works.  Otherwise you are double dipping.  I had a client apply for the advance (tho he didn’t need funds that quickly) and i now had him apply for a PPP loan but the advance will do nothing but complicate the bookkeeping.   I wish he’d not jumped at something he was told by a “friend” without contacting me.  
 

Unless you need cash real fast there’s no reason for the advance.  And I’m not so sure it will come any faster than the PPP funds.  So far finds are coming out quite slowly.  By the way.  It is an amount UP TO $10,000.  The few I know who have received funds were $6,000, $3,000and $2,000 (based on # of employees)   So keep that in mind