Anyhow, the following device
https://ka7oei.blogspot.com/2019/11/hom ... t.html?m=1
is called splitter/combiner, they exist as passive or active ones, the above one has pretty good insertion loss, but willing to compensate it, one may just add an LNA between the antenna and the splitter, willing to build a simple preamp with enough gain for the task, the circuits found here
https://worldradiohistory.com/Archive-D ... 197911.pdf
starting at page #14 in the pdf, may fit pretty well, the preamp will then be connected to the single "shared" port