I agree with some of the above posts, that for really precise inharmonic spectra and corresponding tuning, you should use software synthesizers. It should be relatively easy to come up with inharmonic, additive synths and custom tuning in PureData and bring that to some programmable DSP module like Befaco Lich: https://www.modulargrid.net/e/befaco-lich
However, if you want the challenge and stay in the analog domain, then there is another option. You can use any standard VCO and route its output through a frequency shifter. When you couple the FM input of the VCO with the right amount of frequency shifting CV you can get inharmonic spectra and custom tuning. The downside is that high quality analog frequency shifters are expensive modules: https://www.modulargrid.net/e/cwejman-fsh-1-