That's a very good question!
I don't think anyone has been working on this in terms of code at least.
My personal opinion would be that it would be an interesting thing to support within the community though!
I think if it's simply plasmid detection with a single tool (or a couple that do the same thing), it would fit in the scipe of mag - as it would sort of be equivalent to e.g. genomad or tiara for 'identifying' viral or eukaryotic sequences.
However if it would be more involved, it would be better in a downstream pipeline, e.g. similar to what #C05E9C2B2BG was trying to do.
I'm not sure if it would fit in #C02K5GX2W93 because that is meant to be quite specifically gene centric, not for other genomic features (so to say)