Phone cameras are surprisingly good these days. But stills and video can absorb huge quantities of money for little noticeable difference, depending on user skill, editing and presentation.
Every camera will have its strengths and weaknesses. Buying an interchangeable lens camera buys into that system, so choose wisely.
Just about any old camera can take a decent still image. I think the Canons still have the best colours straight out of camera, though others can be improved in edit. I use Panasonic micro four thirds for lightness and portability. I find the typical crop body DSLR too heavy for a day out and about, but individual mileage will vary on that front.
Many stills shooters will advocate for full frame bodies and that's fine. But the cost and added weight over a crop body DSLR turns me off. For a hobby I deem that unnecessary. Plus tiring if I'm on my feet for hours at a time and carrying two cameras, one on a tripod and the other in a shoulder bag.
For video, its different. Editing will need a decent computer processor. So whilst a full frame with no crop or pixel binning delivers great resolution, many home PCs will choke when trying to render the files.
For vlogging or general upload, 4k isnt necessary but can be very handy to have during editing. I typically use a high res non 4k take to capture the footage. The advantage of 4k files is that they can be cropped significantly without much loss of resolution, which is handy in 'run and gun' filming.
For the record, I have a Panasonic g95 for stills and an ancient GH3 for video. I wouldn't recommend MFT for stills, despite using them myself. A good crop body DSLR like ANRs Canon 80D is probably a decent compromise.
I am so looking forward to when the steam trains begin to operate again.