Your baby is definitely showing some good signs, the interest in food and lip smacking are classic readiness cues, and at just over 6 months, she's in the right window. The sitting assistance thing isn't a blocker as long as she can hold her head steady; that's really what matters for safety. That said, the "snacking" instead of full feeds is worth paying attention to, some babies do this naturally when they're ready to explore solids, but it can also mean she's just adjusting her rhythm, so it's good you're noticing the pattern.
I'd suggest starting gently with single-ingredient soft purées (like sweet potato, pumpkin, or iron-fortified baby rice) and watching how she does over a few days before adding anything new. Most mums I know started with just one or two spoonfuls at a time, once a day, and ramped up gradually. The milk feeds will still be her main nutrition for a while, so there's no rush to do too much too soon.
Worth checking in with your child's doctor or polyclinic though, they can give you the all-clear and flag anything specific to your baby's development.