Android: look into "POE" by far the best.
I'll leave it at that.
I’ve been looking into some AI assistants that I can use in my phone without installing any app. (all these can be turned into PWAs)
1- https://labs.perplexity.ai/
You can use LLama2 here or use their own research assistant.
2- phind.com
An AI research and pair programming assistant.
3- gptgo.ai
Basically chatGPT without the need to create account