What I want:
Drive a 17V, 600mA COB LED from a 5V 3A USB powerbank.
Approach 1: Use a boost LED driver.
I have looked through Digikey as well as manufacturers' parametric searches to find a suitable boost LED driver. Unfortunately, the few parts that would work (e.g. the LT3477, almost 7€/piece) are either comparatively expensive, require lots of auxiliary parts or both.
Approach 2: Boost converter in series with a buck LED driver
If I were able to use a regular boost converter in series with a buck LED driver, the selection would not only be far greater but the parts would also be cheaper. Based on a forum post, connecting boost converters in series is only possible if they are of the isolated type (the boost converters I have looked at didn't mention isolation, so I reckon they are non-isolated). Does that limitation also apply to me, as I would connect a boost in series with a buck converter, not two boost converters (as buck/boost converters are very similar, I suspect it does)?
Question: Is approach 2 viable, or do I have to bite the bullet and go with approach 1? Do you have an alternative approach I haven't thought about?