I don’t think this is possible at all due to structural differences in the model’s design, but I may be wrong.
Reference this if you want more clarity on what I am saying - Comparison between BERT, GPT-2 and ELMo | by Gaurav Ghati | Medium
" Drawbacks: GPT is its uni-directional nature — the model is only trained to predict the future left-to-right context ." - from the article
Hope this answers your question