Is it possible to convert Transformer Tokenizers into Onnx format?

Lets say I have some Transformer model LayoutLM (but it could be any model from hugging face) then I would like to convert it to ONNX format , but before applying some Sentence we have to tokenize it via Bert or other tokenizer, I already know how to wrap model into Onnx but I have troubles with converting tokenizer to onnx , any suggestions ?