Maybe, than again Red Hat was bought for an astronomical some by IBM so they were doing something right. Ubuntu still looks like it is doing well. I do not know how Suse is doing but they still exist.
So I think commercial foss is not a failure but probably difficult to maintain.
Yes sorry I meant trademark. It is just visual such as graphics in games that are copyrighted. That is why you still need to buy Doom eventhough the code was open sourced in the 90’s.
RHEL (Red Hat Enterprise Linux) would be an example. I am sure there are more but I am not well versed enough. There is also Ardour but I think that is more if you want a binary and build the software from source.
Not financially free but free as in freedom. Although most foss does not need to be bought, but there are foss programs you have to buy and after you bought it you are free to do with it what you want. Although this depends on the licence and copyright. For example you can fork the code and resell it (under certain licences) but due to copyright you can not use certain things such as graphics, fonts and name (depending on their licence).
ThFair enough most are free as in free beer and free as in freedom. But that is also the reason why open source is so badly funded. I donate but that is nowhere near enough. I am not Valve, Google, Microsoft, Amazon, etc… Do not have the funds to hire devs.