Fingers crossed, no more warning lights going off

My battery's at about 226,000 so far. For cabin filter, you can go with the Toyota one, or switch to some aftermarket options (Fram CF9846A is odor-absorbing, for example). Besides the cabin filter, there's of course the engine air filter, and if there are any of the other scheduled maintenance items shown in the manual that you're not sure have been done, doing them would be good.

If you have a reason to think the injectors might be dirty, what seems the most effective way to clean them is to remove them and send them to a reconditioning service, which replaces the screens and O-rings, uses pressurized solvent to clean them, and returns them with quantitative before and after test results. There is kind of a PriusChat experiment going on;
I had mine reconditioned that way (mostly just to get the test results, which turned out to be great even before cleaning); another PC member, astrolink, had a bad rough running problem cleared up (and the tests on his injectors showed a clear difference before to after); another member C Clay conducted the same experiment only his engine issue wasn't fixed by it (not surprising, as his test results came back saying the original injectors were fine).

So, the experience so far (N = 3) seems to show that a Prius can have injector issues and run better after thorough cleaning, but so far in 2 of 3 cases the injectors test out just fine before cleaning, even at high mileage. Also, in astrolink's case, a couple treatments of injector-cleaner-into-the-fuel-tank had been tried already, without improvement; it doesn't seem comparable to a real off-the-car cleaning.

I don't know that I'd bother with them unless you have an engine roughness issue and think they could be to blame. You can also use Mini VCI or ScanGauge, etc., to look at the "long term fuel trim" parameter; close to zero would suggest no concern about the injectors, close to 20% would strongly suggest cleaning.

If you do have any reason for concern about the injectors, the way the experiment has been working, for starters astrolink bought new injectors to replace his old ones, and I picked up the tab to recondition and test the old ones, and ended up with those injectors and their test certificate. The next person swapped those in and I ended up with his old ones and their certificate after reconditioning, and so on. I can ship them out for the reconditioning cost I paid ($83.60) plus shipping. Saves waiting on the turnaround time to send a set for reconditioning and wait to get the same ones back.

-Chap