Warp engineer here - yes, you can use OpenCode or Pi as comparison points; our CLI has BYOK, Supergrok subscription support, or our own inference to connect to frontier / open weight.
The main reason you might try it is the shell access. We made CLI commands runnable in an agent session in the foreground, similar to our terminal agent. It means you can `cd` into different directories during the session, or run interactive commands like vim or REPLs in the session. One reason is convenience (it's nicer to cd around projects and keep the conversation going) and another is visibility (you can run a REPL in the foreground and tag in an agent to help and control that REPL). We're curious how others like working this way. It's pretty convenient.