Perform model fit evaluation in Bayesian way when sampling from the custom distribution is not known

I’ve implemented the base InverseGaussian in this gist, and then a shifted version:

Adding the logcdf function to the InverseGaussian should allow the shifted version to work with pm.Censored, but for the point of doing prior and posterior predictive I assume you don’t want to censor the values anyway, so you can just write a model with the “uncensored” version to do predictions?