I have good experiences with my G19 Magpul mags and would really like to see Magpul making M&P pistol mags.

Just wonder if the market would support it, personally just think wouldn’t sell very well. My duty magazines are metal and I wouldn’t switch. Even when I think of buying them for my Glocks, I just buy Glock it’s just a few dollars more 13 vs 19 per magazines.

Yeah I don’t think they’d sell very well either. But I may be wrong. Magpul is one of those universal brands that seems to be able to stamp their name on a turd and sell a few hundred thousand units.

If I recall, the material thickness of the Glock mag tubes which Magpul makes is roughly the same as the stock mag tubes.

Unless Magpul starts making metal mag tubes, the thickness of the mag tubes would by necessity have to be increased over that of the stock S&W parts.
That would reduce capacity.

Other than possibly providing a lower price point or for the reason jljones commented, I see no market for them

Don't see why magpul should bother. M&P mags are astoundingly reliable and drop free and are inexpensive, and only work in M&Ps. Glock mags are roughly one Brazilion times more common and are used in multiple carbines etc.