I ran out of time to show it, but my #droidcon session’s chat demo included an implementation for Google PaLM as well as OpenAI (using the chat and embeddings APIs).
Code:
https://github.com/conceptdev/droidcon-sf-23/
Google's own quickstart and sample:
https://developers.generativeai.google/tutorials/chat_android_quickstart
(with link to get a PaLM API key)