I haven't heard about myocarditis in kids with Sinovac, but they only recently started vaccinating. Since it's different technology from Pfizer, hopefully it won't be an issue.

My husband was able to get a Pfizer booster yesterday. He got lucky, today is a holiday, so yesterday they closed early. He got the last available dose.

They are loosening up the border a bit. Foreigners can come in, but they have to be vaccinated and have a QR code for their vaccines (a simple vaccination card won't work). It takes about a month to validate a vaccination. Upon arrival, they need to show a negative test and quarantine for 5 days. Government employees will be checking to see that people are quarantining in the place they indicate.

It seems it is more to allow family visits. I doubt many tourists will want to waste 5 days of their vacation, or in a worst case, they will try to get around the restrictions. If you are visiting family, you can stay with them, at least, for the quarantine period. I am sure there will be more online whining from the entitled that this isn't enough.