Is sandbox available as standalone product?

Is there some way to install Comodo Sandbox (so I can run my web browser inside the Comodo sandbox) in standalone fashion? (i.e. without installing HIPS/CIS/etc)

(I am required to run McAfee Endpoint Security, so I think Comodo CIS/Firewall/AV/HIPS won’t work with that)

There isn’t. The closest thing would be the Cloud AV browser extension and plugin for chrome (not the same as the actual Cloud AV program). However it only analyses (and potentially sandboxes) downloaded files and doesn’t virtualise the whole browser.
If McAfee doesn’t include a firewall itself, you could still use Comodo Firewall. If it does, you could use the actual Cloud AV from comodo and just disable the AV component.

What about Secure Shopping? Stand alone installation: Comodo Secure Shopping, Safe Purchase Online, Secure Online Purchases | Secure Shopping

Isn’t Secure Shopping to protect the data of what you execute inside of it from processes outside, whereas the virtualisation of the sandbox does the opposite?

If the only need is just to keep it away from any conflict with McAfee Endpoint Security, it should work . . . haven’t used McAfee for years, but worth a try