The V6 is the 3.0 so that weeds out one possibility anyway. Oil pumps seldom ever fail and if an oil pump fails then odds are the entire engine is wiped out.
The reason I asked about a timing belt was to try and determine if there was a problem with that particular job that may have led to the current problem.
Keeping mind this only a possibility, a belt tensioner or idler that was not replaced at the time could possibly have been trying to seize up. This could lead to the engine trying to lock up and of course this might lead to the oil light being illuminated.
Eventually the tensioner may have seized for good which is where you are now.
There are other possibiities related to the oil pump being stripped out (near zero in my opinion), a camshaft trying to seize up due to lack of lubricant, etc.
It's near impossible to make much of an accurate guess without hands on the car.
The timing belt change followed so shortly by something like this does sound odd although I am by no means accusing the shop that did the job of botching something.
What I would do is pop the timing belt cover off and take a look inside there first. If nothing appears to have failed then the next step would be to drain the engine oil and pull the oil pan and preferably at least one valve cover to check for sludging.
Sludging can coke up (meaning hardened oil) the oil pump pickup screen and at some point may get bad enough to prevent oil from reaching the pump. It's not long them before the engine is toast.
Toyota has had a lot of complaints over this issue and extended the engine warranty in a PR move but I think the limit was 8 years from the date of sale, which leaves you a day late and a dollar short.
Hope some of that helps anyway.