React Native game, MongoDB or Firestore - mongodb

Question

I am working on a multiplayer react native game for android, it's just a text game.
For now, I've been working only on the client side but I'm slowly getting to the point where I need to choose a way to manage data. Since I'm always trying to learn something new - first time using RN too -, I came across Firestore and I'm curious if it's a viable choice from my project.
For example, in this game you can buy/open companies. If I were to handle this action in nodejs + MongoDB I'd send a JWT token to server/api/newcompany.
Assuming I'd have 2 MongoDB models, Users with all the user info and Company a list of all Companies in game. First I'd check if the User had enough money to open the company and then return some message based on that, my code would be something like this:
// routes.js
...
router.post('/api/newcompany',AuthCheck, Company.new)
// controllers/company.js
...
new: async function (req, res, next) {
if (!req.body.companyType || !validCompanyType) {
return res.status(200).send('invalid/missing message and other failed checks')
}
//assuming token data would be passed from auth middleware and would have company prices somewhere
const user = await Users.find({id:token.userId})
if (user.money < companyPrice) {
res.status(200).send('no money')
} else {
const newCompany = new Company()
newCompany.name = req.body.name
...
new.Companny.save(function(){
res.status(200).send('all good')
})
}
}
Looking at Firestore I'd have the same 2 documents as above. Users with a list of sub-documents(the users) identified by their IDs and a document Companies.
Would I be able to do the same users checks as above?
How would I handle that? Would I use the Firestore Rules to check the user has enough money or would I use my server with admin SDK as an intermediary to handle more complex ops and use the direct Firestore connection just for retrieving data?
Thanks for your time.