managing a game in house with a workflow in place is already a challenge, managing it over upwork will be nightmarish i imagine and in most cases counter intuitive, you need at least one good lead fulltime to gather the data and put it all together, i can imagine upwork for maybe certain individual asset creations.
time and coordination over long distances can end up wasting more money for what you put in, just saying watch out on these factors.
to my knowledge the amount you are willing to put may only land you an early prototype for the type of game you have described.
i wouldve said it could be done if you were a dev as well, but in your case you will really need a lead generalist who understands the entire process and is also good at one thing at least.