if you're still interested... yeah the easiest way would be to run it on a computer that's on 24/7. A cheap VPS is fine but a home PC is also fine if you already have it running all the time. Comrade SleeplessOne made a library to make it easier: https://github.com/SleeplessOne1917/lemmy-bot

There are some example bots floating around various places that you might be able to adapt to your needs