Good breathable option for heavier baby?

I currently have a nine-month-old who's very leggy and on the heavier side at 23 lbs. My husband and I are visiting NYC with him in August -- he'll be 11 months old, and also probably walking by then. We'll be doing a fair amount of walking and I assume the weather will be pretty hot at that point. I'm looking for a baby carried that has structure that can preferably by worn front or back. Bonus points if I can sit down while wearing it. Breathability the baby and also mom/dad is a must! It looks like the Boba 4G is a good one, but I saw other posts on Reddit where folks were saying it killed their backs due to too little structure and some saying it was too hot. I'd love to not spend a ton of money, and if I do end up spending more than like 150, I would love it if it the carrier were one that would last us a few years and/or had an insert available so we could use it with a future baby from a younger age.

Thanks in advance! Signed, a tired mom who is getting confused with all of the info available