From my understanding, when a solution like DMSO with PFAS enters our blood stream it gets highly dilute. Solvation binding of solvent (DMSO) and the solute (PFAS) now has to compete with binding from all sorts of other proteins, fats, carbohydrates, etc.
In this incredibly dilute state, the previous mixture of molecules now spreads out and gets taken up by different tissues. The tissues that take up the compounds depends in the molecular properties of the compound in question, so something like PFAS which are highly lipophilic (iirc) meaning fat soluble, they will be taken up by cells pretty readily as they can easily cross the lipid bilayer membrane but will be stored in adipose tissue and continue impacting those cells and possibly be slowly released over time to impact the organism systemically. This of course will depend on initial dose concentration, duration of exposure, adioposity of the organism, along with a multitude of other factors.
The study of how compounds circulate in this way is a subfield of pharmacology known as Absorption, Distribution, Metabolism, and Excretion (ADME)