Should global health donors focus on R&D?

Global health R&D strikes me as having very high expected value, but might be difficult for governments in low income countries to justify to voters when it could spent on urgent object level health interventions which produce benefits more quickly.

Does that mean donors should focus more on R&D (eg—give more funding to CEPI than to the Pandemic Fund)? Is this idea fleshed out in better detail somewhere in the global health world?