Use of a standalone MongoDB server?

We are not currently planning to implement running mongod and cryosparc_master processes on separate hosts.

Not necessarily.
For mongodb v3.6 + the WiredTiger storage engine, which CryoSPARC v4.3.1 uses, nfs mount options are documented
For the current version of mongodb, you can find, with respect to nfs, both avoid and, again, mount options.
Did you consider hosting cryosparc_master software, along with the database, on an off-cluster server? It is possible to host multiple CryoSPARC instances on a single computer if you ensure non-overlapping

  1. port ranges
  2. sets of projects directories
  3. database paths