failover on multiple indexes

[yuzhichang]

My scenario is:
The access to pypi.org is slow, or even broken very often. There are some public pypi mirrors here but none is stable (reachable, fast, can serve query and downloading) enough. These mirrors are hosted by famous companies or universities so I trust them.
I want "uv pip install" to pick the fastest and up-to-date one among them. If it's broken (reachable but cannot serve query and downloading for some unknown reason), the try another one.

As far as I know, neither pip nor uv failovers on multiple indexes. This forced me to change index from time to time. This is annoying.