I haven't flown out of DPS on QR, but have used Lounge Key to access lounges when flying on low cost carriers.

My memory is that there are 2 main pay-on-access lounges which are used by most airlines. The food was definitely better in one than the other (sorry, can't remember which) and alcohol options were very limited in both. One of them had no natural light, the other did have windows. Neither of them was conducive to staying more than an hour or two.