Great read, thanks for your thoughts! I'm thinking of getting a color meter for a while now and now I'm wondering if there's something similar available for android smartphones?

Have a look at used Nikon E Series lenses, they are mostly underrated. I bought a 50mm/1.8, a 28mm/2.8 and a wonderful 75–150mm/3.5. Paid around 150€ for the bunch... and you get manual aperture rings!