I don't think Mastriano has mentioned 2020 even once since winning the primary. His main problem is money, but that should flow in later on.
I think its pretty uncontroversial to say now that Mastriano has exceeded everyone's expectations.
If Mastriano doesn't mention 2020 and Shapiro makes it a centrepoint of his campaign (which is looking likely), this might have some VA-GOV parallels (I know Youngkin is a better candidate than Doug, but PA is double digits more Republican than VA).
The only reason Mastriano is "exceeding expectations" is he's doing better than Oz and looks better in a relative sense. He's not doing well in an absolute sense. His fundraising is shot and he hasn't led a single poll. The VA-GOV comparison makes no sense whatsoever because Mastriano has a completely different profile than Youngkin.