Virions are strictly limited to a specific size range because the proteins that make up their coat (mixed in with the lipids they steal from the cell) create a specific structure which is limited in size (like a clathrin cage).

Exsosomes are not released in the quantities that are seen in the electron microscopy that shows the virus. They are not exosomes. On the contrary, they have specific proteins that create the cage that come from the viral RNA as stated above.

When a cell blebs it looks similar to the EM of virions,(blebbing is what happens during apoptosis) but Blebs are not restricted in size like the virions are. Virions have a unique phenotype under EM, and the pictures of SARS-CoV-2 look just like what one would expect of a virus.