What should I do with money that I don’t need “now?”

Hello!

Im a 29M deployed overseas right now. I would say i am frugal with my earnings. I give myself no more than $300 dollars per pay period. Right now I have enough money for bills for a whole year when I get back home. Additionally, I’m maxed out for my Roth IRA, and have been contributing 10% to my TSP. The rest of my money that I don’t “touch”, are sitting in a HYSA with ally bank.

My question is, I know my money can work harder for me. I’ve done some research on ETFs/Mutual funds and my eyes are set on VOO. Would it be a wise decision to put the “dont-need-now” money in VOO to set it and forget it? Thanks!