It's interesting to see this one launch (yes yet another sandbox.. I was getting worried we'd not seen one for a few days)

SlicerVM (est. 2022) is already used for prime time, not "free as in beer" but has pretty reasonable individual plans that include all features. Shares the core code with actuated. (Creator of both speaking here)

Feel free to take a look and see if gives you a little more than the others you mentioned. If not no problems, I realise some folks prefer free stuff.