Quite frankly, I am interested in the actual answer. My gut feeling is that renewables received more R&D than nuclear fission but I would be happy to correct my misconception there. But the IEA numbers are really small. 1.3 billions for 2 years of nuclear R&D? France's CEA, that oversees nuclear R&D (among other things, but mainly) has a 5 billions yearly budget.

R&D of the 21 top leading solar firms has exceeded the billion since 2017: https://www.actu-solaire.fr/a-10681-les-depenses-de-r-d-dans-le-photovoltaique-depuis-cinq-ans.html

The IEA numbers seem biased in that they just include a fistful of countries. They do not include China (that does a ton of solar R&D) and include France (one of the last to do nuclear research).