>Pump means everything to someone who is looking for visible muscle mass.
It's don't. Here is some random article from google about pump training vs strength training.
>https://legionathletics.com/muscle-pump/#:~:text=As%20you%20know%2C%20pump%20training,more%20muscle%20growth%20over%20time.
The essence is that strength training is just more efficient than pump training because it takes less time
>I would need to lift insanely much and eat a lot in order for me to gain significant mass in that situation.
Muscles are made of something and If you want to gain muscle you have to eat a lot. There is no difference in the style of training. Look at bodybuilding videos on youtube - they are mostly about eating. Training is secondary. Maybe even tertiary after the drugs they take.