Actually, I was able to do that with Anvil.
After heroku shut down their free tier plan, I was looking for a reliable place to host my bot. Since I was already paying for Anvil, I thought to myself - why not use Anvil for that?
The basic logic is to create a scheduled task that runs every minute (but since that background task will be up forever typically, the next scheduled will not run).
After a week or two, when the background task vanishes, you’ll have the bot back online in less than a minute. My bot is able to handle almost 4000 servers that way without much issues.
It’s not the best way to host the bot but it does work. Although, you’ll need atleast a Personal Plan (so don’t go for this unless you are already paying Anvil).