When Ruby eats at home, we put her in her booster/high chair. She has a tray snapped on in front of her, keeping her safe and secure in the seat. And when we go to a restaurant, she sits in a high chair there too. I've not thought about transitioning to anything else because she's not tall enough anyway.
We have a small outdoor picnic table that the kids used when they were younger. It's become our art table, among other things. With the weather being so nice for the last few weeks, we've been eating outside more, and Ruby has started to sit at that table with the big kids. No straps, no trays. I thought it may be a struggle to keep her there, not wandering around, or that she might fall back because she's used to having something to support her torso. But no...she's doing just fine.
Ruby is loving this new 'grown up' table so much that she totally shocked me last week. We had four other families (and kids) over for dinner. The adults ate at our dininng room talbe in eye shot of the outside area where the kids could eat at the kids table or our bigger outdoor table. A few started wtih Ruby at the kids' picnic table, but one by one they all congregated in the screened in deck. Ruby sat at the table all by herself and ate all of her food (pretty neatly for her) for over 15 minutes.