We can integrate Tally with any Software using tally XML API We need to post xml request to tally in specified format to get data Ex: To get Ledger from Tally we need to use this XML you can view similar xmls here We can use any programming language but process is same Post data to tally with required payload XML Process the response received Post it to Firebase using Firebase API we can also use TDL but I am not aware of that
Need to host REST function in firebase project. I think from Sept 21 its available for asia zone (earlier avbl to Europe only). And through endpoints its possible. I have developed a tdddb a flat database for tally to overcome such problems. If still you have requirement pls drop a note. If required I will show you a CRUD application for firestore. (Firestore is database and firebase is project ie it includes functions, databases, hosting, storage etc.)