Rokinon has made such lenses for efm mount e.g. 12f2. Being manual is not a big deal for such wide lenses as often focusing to infinity is all you need.
I certainly would want an autofocus lens, although I'm sure the Rokinon/Samyang 12mm is good.
I have the Rokinon 12mm f/2 regularly mounted on my Canon M5. (For those who are not aware, the Rokinon is the same as the Samyang 12mm f/2, lens, just badged differently)
It is a very sharp lens, with great contrast levels (including micro-contrast). It is a joy to use due to its small size, good build quality and usable focus ring. It allows a really useful equivalent of "FF" 19mm field of view, which is great for many landscapes, architecture and more.
It is also a fantastic lens for astrophotography - with low coma and very good image quality, even towards the corners wide open at f/2. Actually, astrophotography is the main reason I bought this lens and entered the Canon EOS M market - buying an as new 'M5' here in Australia. My copy focuses at infinity just a fraction before the focus 'hard stop', so I have the process down pat for .
The M5's focus peaking makes critical manual focusing (MF) - at less than infinity - quite user friendly. Would I like and use accurate and fairly speedy AF? Yes, sure... all the other lenses I own (EF, EF-S, EF-M etc) are auto focus. But I can certainly live with this lens being MF!
I look forward to what Canon will be providing in their next EOS-M line-up / models. The EOS M50 presents an exciting indication of what may be in the EOS M5mkII (or other similar models). In the meantime, I enjoy taking photos with my Canon DSLRs and my mirrorless M5 body, with the various lenses I have for them.
Regards
PJ