I am personally a very arrogant chef, so I am pleasantly surprised at your suggestions of preparation.
Minor variations i might make are to instead, if you can afford it, opt for the fresh pre-sliced stirfry mix in your grocer's produce department, as it will come out much better with more vibrant flavors among the veggies over frozen mix which can kinda taste uniform.
If you aren't reusing rice from a previous meal and making it specifically for fried rice, I would also consider adding a scoop of chicken or vegetable boullion to the water you are cooking the rice in. It adds a bit more heartyness and nutrition to the dish without altering the flavour too much.
100% agree on oyster sauce, but also keep in mind it doesnt add much salt on its own so the soy sauce is very important, and if you didnt want to alter the flavour too much, just adding regular salt on its own could help. The main difference between most american's home cooking and professional restaurants, is that we at home tend to undersalt our food and thats why the flavours seem more pronounced at real restaurants. If you have enough soy sauce etc then you wont need as much oyster sauce as you think you will.
Butter is good, but I find olive oil doesnt mesh with the flavours being used as much. Sometimes a light amount of vegetable oil with some drops of sesame oil is enough. Alternatively coconut oil is a good addition too and has a higher temperature limit but be careful it doesnt overwhelm the flavours if you are someone who tastes it easily in things.
One of my favorite go-tos to add a bit of spice to this is Garlic Chili Oil,
https://www.sbfoods-worldwide.com/lp/us/umamitopping/It isnt specifically made for cooking but it just adds so much substance.
Additionally, mixing in some ginger and garlic can help the flavour. Ginger is particularly tricky to find pieces that grate well, but dont be afraid to by the tubes of ginger paste, also located in the produce section by the herbs. They last a while without too many preservatives. Always opt for the stuff in the refrigerated section over the shelf-stable jarred stuff when you can. You'll have to refrigerate it after opening anyways, but its much fresher with less extra stuff.