On the Uzbek side I was assaulted by countless taxi drivers but I knew there should be a local bus as well. Just glance over to the parking lot on your right (where all the taxis are as well) and you'll see a larger bus parked in the middle of it with 'Andijan' behind the window. Just wait for the bus to fill up and the trip to Andijan take about 40 minutes orso.
In Andijan you are dropped off at a large parking/bus station, where you are assaulted by taxi drivers. I needed a ride to Tashkent and this was the first time during my trip I seriously experienced the downside of not speaking local language/russian... I ended up sharing a taxi with an elderly Uzbek couple and guy in his 30s, who fed me Uzbek food the entire way to Tashkent. It was a very fun experience.

(additional tip for those traveling onwards: I was dropped off at Tashkent train station around 16h-ish and was lucky enough to get a ticket for the night train to Buhkara for that same evening still. Pretty sweet to make it from Osh all the way to Bukhara in 24 hrs just traveling on the fly:))