How to use a precompiled library in a project with Arduino-IDE
See https://github.com/arduino/Arduino/wiki/Arduino-IDE-1.5:-Library-specification


  library.properties file format
  [...]
  precompiled - (available from Arduino IDE 1.8.6/arduino-builder 1.4.0) (optional) set to true to allow the use of .a (archive) and .so (shared object) files. The .a/.so file must be located at src/{build.mcu} where {build.mcu} is the architecture name of the target the file was compiled for. Ex: cortex-m3 for the Arduino DUE. The static library should be linked as an ldflag.


So with the correct metadata and file layout the precompiled objects should be available.
You'll need to set the architectures property to indicate you're using esp8266 as your tag suggests.

More info on the library manager here https://github.com/arduino/Arduino/wiki/Library-Manager-FAQ including how to add to the public library list.