I'm a purely ecom business. I don't want to buy and keep inventory but not all brands offer dropshipping options, what's a middle ground to achieve? How can I still work with those brands without having to buy inventory? Please advice
You can't force someone to operate in a way they don't want to. You and everyone else face this same issue. I have no expectation that it will ever change. Your dislike of holding inventory is the weak point. If you want the merchandise to sell, and it's only available by stocking, you either stock or you don't carry that brand.
It's a selfish premise to only be a drop shipper. That doesn't make it wrong, but that's your choice. You only add value to the manufacturer in marketing, and their security is in you buying inventory up-front. If you expect everyone to take on the risk other than you, not everyone is going to do business with you.