Most of the funding for the Manhattan project went into the industrial infrastructure required to produce plutonium and enriched uranium.
It will be time to unleash resources once they have a working fusion reactor design in order to build fusion power plants and the industrial infrastructure required to supply them.
Until then they should of course get the resources they need but I don't think throwing money at them will necessarily speed things up.
A uranium-gun bomb has a very simple theoretical basis, but enriching uranium is very expensive (and was even more expensive in the 1940s. Producing enough enriched uranium was the only hard problem in making that bomb; in fact they did not even test the bomb before dropping it on Hiroshima because they were fairly sure it was going to work and wouldn't have enough enriched uranium for a second bomb on the timelines involved.
Plutonium was significantly more easy to produce, but it did require some novel engineering for the implosion lens. They weren't sure it was going to work and did, in fact, test the bomb before dropping it on Nagasaki.
I think the Manhattan project is a great example of where more funds can help; if the funds were more restricted, it's entirely possible they would have gone with the "sure thing" of the uranium bomb instead of spending resources on the less sure plutonium bomb. Trying out multiple ideas in parallel often "wastes" money since if you try ideas in tandem, you will always try the high-percentage ideas first.
It will be time to unleash resources once they have a working fusion reactor design in order to build fusion power plants and the industrial infrastructure required to supply them.
Until then they should of course get the resources they need but I don't think throwing money at them will necessarily speed things up.