Isopropyl alcohol can kill fungus gnats and any of their eggs in the soil. You can spray the soil and plant, but you'll want to keep the plant out of the sun until it dries so it doesn't burn. Doesn't take long to dry. I use 91% alcohol but 70% also works

White bugs could be mealybugs. The alcohol should work on them as well, but someone else may have other suggestions for them. They're also like the plague, so you should move the infected plants away from any others

You'll also want to determine what caused the bugs, so you can prevent it from happening again. Overwatering is a common cause of gnats and mealybugs, or the wrong soil. Succulents like a gritty/gravelly soil, and for it to be completely dry before watering

Mealybugs are bit bigger and do not really move around much. They are oval shape and segmented, and covered in white or grayish cotton-like wax. They do not stay in the soil, but you find them on the plant. They will die if you spray them with rubbing alcohol (or get it on them with a q-tip, moistened in ra if there are just few). They are worse than fungus gnats, so if you see any, get rid of it asap.

What is in your 1st photo doesn't look like mealy bug.

Gnats prefer organic and moist conditions, so make sure there is good air circulation, potting mix doesn't contain mostly organic materials and doesn't stay damp for too long. Get rid of any standing water (for example in saucers), and any plant debris. That way you can decrease population considerably (or even eliminate it), without any spraying. I am not sure if rubbing alcohol helps with these.

I can't see what is in the pot, but looks too dark (wet/damp soil usually does). Also, soil level seems to be too low inside the pot, making air circulation worse. Can you post better photo of plant in the pot pls?