This reminded me of years ago with our ancient Honda Prelude that began making a whining noise from the transmission after 100,000 miles. Our wise mechanic told us to just drive it until it died. That in his opinion it could run a long time makng that noise but it was not worth the investment to try and fix it since it still shifted and ran okay. After a few more years it still whined and ran okay when we donated it to charity.

My point is that his engine could continue ticking and run just fine for another 50,000 or more. Nobody knows. However I bet the trade in value of the car is far less than their estimate for an engine rebuild.
There are so many used 3.5 Toyota engines out there that used ones are relatively cheap these days and most independent shops could do the installation. Some larger wrecking yards also do installation.

You could try a bottle of engine flush before changing the oil again. Liquimoly makes a good one. You just pour it in and idle the motor for the specified time before changing the oil again. If there is some sludge in the valve lifters or VVTI it may help clear it out and reduce the ticking. https://www.liqui-moly.com/en/us/pro...0065.html#2037
Amzn and many auto parts stores have it.