I mean sustanon has more PIP than test E/C so dunno if it would be pleasant but if its a legit TRT dose say 100mg/week and you inject daily/EOD to minimize each injection I dont see why not?
trt doctors will do subQ injections for their patients but it is a tiny amount that is once a week at most
if you are doing an actual cycle you don't want to inject subQ because you will quickly run into problems like abscesses and scar tissue injecting that much gear with a slin pin