Yeah, so presumably you need exponential control even if it’s not necessarily 1.0000 V/oct, and then you probably would want some level of temperature stability even if it’s not necessarily rock steady. A couple discussions:
https://www.schmitzbits.de/expo_tutorial/
These provide a control current, how to use that to control your oscillator is the big question. LM13700 is the first thing that comes to my mind.