You should never use an LLM/AI Chatbot with a third party service for anything that could be confidential, private in nature, or may have to do with your security.
All of the LLM/AI providers can read your contents. The only thing between them and your chats is "trust," and we've all had promises broken on us before.
Trust is not security.
Shameless plug: You can definitely use IPv6.rs and Cloud Seeder [1][2] to run Ollama and OpenWebUI on your own computer (confidentially) and access it via TLS remotely (via phone, etc.).
[1] https://ipv6.rs/cloudseeder https://github.com/ipv6rslimited/cloudseeder