While I have a protoype working, as I mentioned previously, I have an issue of not having an appropriate connector for the two sensor modules I have. I actually found ONE manufacturer (I-Pex) that provides one that could work for one of the two models. I contacted them and requested a sample, however while they were nice it was basically "we cannot pay for shipping this product if you are not developing something commercially and have your own company". So, at the moment, I guess I will not get a connector.
The remaining option is to design a footprint for the sensor which has little holes in the pads. In theory I could add solder to the PCB and FPC and then melt them together this way, but it is a bit tricky and I'm not sure it will work.
I have written the schematic for the circuit though: I found appropriate PSU ICs for the 1.8v and 2.85v supplies and also included the MOSFETs for logic-level conversion. I have not yet designed the PCB as I'm not currently motivated to continue this in this way. In any case, I will most likely finish the PCB design in the future, when I make an order on digikey for some other parts and then I can order the required components for this board. Then, I will probably build a complete protoype, at least to finish this with something built. I will eventually decide if there's enough interest to work on this further or not.
In reality I lately became more motivated in picking up my BicycleCompanion project, for which I already have a working protoype. I want to do a second version with many new features and also with several improvements. Thus, I will direct my focus there at the moment.
In any case, let me know if you have any particular interest in this project or any questions or comments.