@suatozkan While firebase cloud messaging cannot be used in the regular expo configuration without detaching, I believe that firebase cloud functions are possible. Would using await + fetch work, perhaps as described in this medium article here: Our extensive experience with Cloud Functions for Firebase | by Tomáš Bezouška | Step Up Labs | Medium ?
There have also been accounts of Expo users getting firebase cloud functions working in this thread here: Expo and uploading image Blobs? - #14 by tscans