> content can load without the blocker being ready to

That issue does not exist for uBO Lite. I specifically wrote in the FAQ under "What are the upsides of an MV3-based content blocker?":

> For Chromium-based browsers specifically, MV3-based content blockers which are entirely declarative will properly filter at browser launch, which is not the case for MV2-based content blockers

uBO Lite is entirely declarative, so it filters properly at browser launch, and I literally give an actual example of this in the following section, search for "filters properly at browser launch".