I just had a weekend with tourists in Beijing. They were able to use Alipay with their CC. They did not try to set up TourCard. More first-hand experiences about that would be appreciated.

I would not use WeChat Pay. You risk having your account audited 4-5 days into your trip (happened to some friends of colleagues previously) - WeChat seems to be a lot more sensitive about payment stuff than Alipay.
Cash was accepted in touristy areas, but change is usually hard to come by (as you'd expect).

Just like everything in China - things are hyperoptimized to get as many people through the system as possible, but if you're an exception - you're on your own. All foreigners (whether they're visiting or living in China) are an exception - so be prepared to be frustrated at times