Some tips based on my own experience:

• Holofly esim works well as a mobile sim (with built in VPN) though I hadn't tried others
• Having a voice/camera translation app is extremely helpful, though if you don't have an esim/VPN then good luck using anything Google, because their apps are blocked (rightfully so). Apple stuff is is allowed and works AFAIK, and Baidu is popular there, though I confess I never used their apps much.
• For VPN, Astral was really the only thing that I tried that worked. Stuff like Express or NordVPN does not.
• Try to get setup with WeChat. As a foreigner, you can't use it for payment, but it's still very useful for information and reserving tickets and stuff. You'll need an invite to get on it, so I'd ask any contacts you have there if they can do that for you.
• You CAN use AliPay for payments, and I HIGHLY recommend getting that set up before you go. You can use cash at a lot of places, but sometimes even cash won't work, as the Chinese basically use WeChat/AliPay for everything. Credit cards are pretty much worthless.
• If you need a cab or rideshare, Didi app is probably the best way for foreigners, and you can use AliPay for payment.
• You should check your visa requirements and make sure you follow their rules. For example, I believe you have to let authorities know if you're staying in a hotel that was not mentioned in your visa application. Also make sure you pay attention to any covid rules and follow their requirements. Even though "zero covid" is over, the Chinese government still takes it somewhat seriously.
• Chinese people are VERY friendly in my experience, and they're more than willing to help out tourists assuming they're polite. So don't hesitate to ask for help if you need it (this is where translation apps are useful) and this includes the police in China, who are way more friendly and chill than cops in the US.
• The western media would never tell you this, but China is actually extremely kid-friendly. There are lots of options for kids and most places cater to families, so your kid is going to love it.
• Also on the topic of being kid-friendly, China is the safest place I've ever been to, hands down. It wasn't uncommon to see young kids running around the city at night without parents there, because they know nothing bad will happen.
• Museums and historical sites in China are absolutely mind blowing. You should visit some if you ever have the chance.
• If you need medicine, it's amazingly easy to get it at a Chinese pharmacy. They do prescriptions right then and there and you don't even need to see a doctor, though what they carry might be a little different. Also, they'll have herbal remedy stuff that really does work. I had stomach pains and they recommended some of these herbal tablets. I was skeptical at first, but that stuff worked better than anything I could get at a drug store in the US.
• Ok, on the topic of being vegan there, I'm vegetarian and even just being that was difficult in China. Animal products are used in a lot of foods there, even stuff some might not expect, like fried rice being made with lard, ma po tofu using meat for the sauce, etc. You can try ordering food without meat but the language barrier can make that difficult. One thing I'd recommend is to plan ahead and try to find food places that are explicitly vegan. A regular food place likely won't have many meat free options, but there might be vegan places where you don't have to worry about it. Where I was has a big Buddhist community, so there were at least some veg/vegan places run by/for Buddhists. I expect big cities have more options like this than rural places. Also, hot pot or buffet style restaurants might be a good bet as you can pick and choose from more options. Just be careful they aren't using beef or pork broth for the hot pot.

Sorry I'm done rambling. Hopefully this was helpful, and I hope your trip is awesome!