I thought this would be one of the few projects that are finished and done and that's it. But of course I found another version of the ST7735 display, not in the form of a module, but a bare display, with resolution of 80×160 and diagonal of just 0.96", and of course it fits perfectly on the D1 Mini shield, so I just have to do it. Here's a mockup, using a PCB for a different shield:
The display is SPI, of course. The PCB has been ordered already (I waited for the display to arrive to make sure I get the dimensions right), so the project should continue in a few weeks.