None of this would be even remotely effective and it would immediately fail and blow up in Biden's face. Manchin would just laugh off Biden's threats and Manchin knows Democrats have exactly zero leverage over him. Zero.
As for Sinema, she's already going to get a primary challenger and I'm sure she knows that if she tanks Biden's agenda the party will throw her to the wolves. As for cutting funding, Biden is going to use executive action to cut off funds to a potentially vital swing state? That's a terrible idea! Sinema already knows she's getting primaried and apparently that's not enough to get her to act responsibly.
The real answer is there is no way to force these two to comply so no I don't have any ideas. Basically they have a huge amount of control over what ends up in the bill and there's no way to change that. Sinema should be primaried and removed but until then we're stuck with her. As for Manchin, he's the single most valuable senator in the country right now and so he basically gets to do whatever he wants.