Fanny pack convertible to backpack, with back support
I did already see a post on this reddit of someone asking about fanny packs that turn into backpacks but some of those products don't get sold anymore and I haven't found what I'm looking for yet. Now this may be very difficult of me to be asking for, I'm not sure. I have a very bad back and prefer bags that have a waist band so part of the bag's weight is on the hips, and a cross chest band to keep the shoulder bands from pressing against the outer part of the shoulder and armpit.
I'm looking for this bag for a vacation where the bag will be a personal bag on the plane, and on the vacation itself it'll be a bag for phone passport and stuff to be turned into a backpack if I need to carry more or to carry purchases.
I'm specifically looking for a convertible because I don't want to constantly be carrying a backpack, even with the extra support it really does a number on my shoulders and back. And I don't want to be carrying a big bag on my back when it'll probably be mostly empty for a big part of the time.
Does anyone have recommendations for a fanny pack convertible to a backpack with some extra support, or maybe places that would be able to make something like this?
Preferably places that ship from the eu to avoid high shipping and processing costs.