Lemmy has an API and Reddit has an API, so, what you want shouldn’t be too difficult.
If you don’t want to start from scratch you could fork something actively maintained that uses the reddit API already, like tootbot, so that you only need to implement the Lemmy side.
It’s possible
I want to know how such a bot can be deployed.
i believe they typically run as a service on a computer, monitoring the subreddit via the reddit api, the when it finds new stuff, it posts it onto lemmy.
I am yet to see an implementation of this between Lemmy and Reddit. That does not help.
If you don’t mind it being a different sublemmy, you can just request it at !requests@lemmit.online.
Can it be done, 100% yes.
There is probably a rss reddit bot.
Here’s a lemmy rss; https://lemmy.ml/feeds/c/antiwork.xml?sort=Active
Or you’d have to commission someone. I got name, but no idea what price he charges.
If you get it setup, ping me! I would want to set some up too.
I’m interested in something similar. I want a bot that reposts the top 3 daily posts from my favorite subreddits to their Lemmy equivalent. I don’t want to flood the Lemmy communities but I think we can all admit most of them could use more activity.
Example: !whowouldwin@lemmy.world has received 3 posts ever as opposed to /r/whowouldwin/ which has over 400,000 subscribers and receives dozens of unique posts every day.
If you stay within the reddit api limits of pay for it, yes.