In a product-led company, it's common that both Product and Product Marketing are involved in conducting customer/market research to inform the roadmap. How can the teams effectively aggregate past and ongoing, new findings, and who should lead this initiative?
This is common, and you should start defining R&R with your PM counterparts. Common knowledge states that PMs should do customer-focused research, and PMMs should do market trends and competitive research. But this varies in reality as many companies have research happening in silos, and it depends on who has the need, budget, and capacity to do it.
Emphasize that no matter who conducts the research, both PMs and PMMs can benefit from and act on the insights. While PMs can use the insights to shift product direction and develop enhancements, PMMs can use them to change messaging and positioning and create new content and programs.
Thus, you can argue for building a central repository of all past and upcoming research projects accessible to various stakeholders. Offer to categorize it based on product areas, themes, personas, etc. This provides visibility and avoids duplicate work.
Set up a core research council or working group to discuss research projects and insights regularly. Offer to be the showrunner for this. This would ensure that everyone feels involved, and you can also use these channels to drive accountability for the next steps.