A relatively comprehensive look into PFAS can be gained by reading the Draft state of per- and polyfluoroalkyl substances (PFAS) report published by Health Canada. [1] The Existing Substances Risk Assessment Bureau at Health Canada (which assesses risks of chemicals that are in commerce in Canada), is increasingly moving towards new analysis techniques broadly characterized as New Approach Methodologies (NAMs) (see section 6.2.5 and 7.6 in the report). So, to my understanding, part of the apparent gap in research is being plugged by the application of models which infer chemicals properties, interactions, and effects without needing to study each of them individually to gain at least an initial idea of how they might harm organisms and environments.

See:

> The evolving landscape of chemical production has rendered toxicological testing using traditional models (i.e., live animals) impractical, and advances in science coupled with ethical concerns have resulted in government agencies, including the United States (US EPA 2021b), European Union, and Canada (Bhuller et al. 2021), committing to reduce, refine, and potentially eliminate the use of mammalian models from certain regulatory testing requirements, where scientifically justified. New approach methodologies (NAMs) are broadly described by the international risk assessment community as any technology, method, approach, or a combination of these that can be used to reduce, refine, or replace animal testing and allow more rapid and effective screening of chemicals. These methods may include the use of computer models or assays with biological molecules, cells, tissues, or organs as well as exposure measurement approaches. [1]

[1] https://www.canada.ca/en/environment-climate-change/services...

P.S. CTRL+F "Health effects" in that report to get a cursory idea of the risks.

Source: worked as a data analyst at the Existing Substances Risk Assessment Bureau