How are liposomes manufactured to put the payload inside?
Manufacturers tailor the process to work best depending on the physical characteristics of each product. In general, they sonicate (use sound waves) at a specific frequency, and at certain temperatures to get the liposome to form with the payload inside.
Some ingredients are more difficult and might hold greater or lesser quantity inside the liposomes. Both water soluble and insoluble can be enclosed, even in the same liposome, but water soluble is simpler.
Testosterone is not water soluble, and is one of the more difficult molecules to form liposomes, but is definitely doable, and very effective, as this study on liposomal testosterone for skin care shows.
As it is not a supplement, but must be prescribed, it is not something we would work on. It also will take years of study and cost many millions to develop as a drug.