Well even though this is r/Nikon I'm going to offer some suggestions that may not be Nikon gear.

In essence if you want a cheap interchangeable lens camera, I will only recommend either the Nikon D3500 or a sony Alpha A6000

Both cameras are entry level APS-C cameras but with their strengths and weaknesses. Compared to other contemporaries in the same price category, they offer up some of the best balance in that they do not have any major weakness that makes me go:" this camera is ok but...".

Eg,

the canon EoS M has a decent sensor but it's a slightly smaller sensor and the EOS M lineup of lens is comically lacking in options

Canon rebel series has an older generation sensor and is smaller than Nikon and sony's and is noticeably lacking in dynamic range compared to the Nikon and Sony esp if you shoot in RAW

The Olympus Pen is a much smaller sensor and image quality particularly at higher ISO is going to be an issue.