Let me put a word in for my bridge camera, a Canon SX50 HS.

Oh - but have you seen my cousin?

I think you would do better with this USM model. WHile it is reconditioned, it is a much better model and rated in excellent condition.:
https://www.amazon.com/Canon-18-135mm-3-5-5-6-Stabilization-Renewed/dp/B07C5QKNRV/ref=sr_1_5?crid=LHY6RPJ4UAFB&dib=eyJ2IjoiMSJ9.ayidVfvOy-33hl_rZEkBXJ3ZvH-98CkbvGI8C3jE-i1VWxb_69p0WQNYKhzWlgMVJI2vQ4SX5O7nwZqVKZreizEGwuSJN7y8yvTNlw48L_Lzi1uJAREyeoaD4Rh0Z-0zIlPoHToLfojsJKysoHYsY0RIKSiexlCIsQd32LiUwr9i6kaopOJvKhDCX7le9W1_L6OPBBfiBPpbG9Ne2GkwhhdEqPblW9_QmZVsRjECTFI.YcbXL3dEk5dnwWqyFk9IrvLW0MFo0waDTbnsff1aPvA&dib_tag=se&keywords=Canon+18-135&qid=1713372948&sprefix=canon+18-135%2Caps%2C81&sr=8-5

While it may not be for perfectionists, a very portable solution is a bridge camera. While I have a Tamron 150-600 G2 lens, I often go to my SX50 HS for a long shot.

You also left out the fact that the 2 cameras have different pixel counts, 20% different.

I highly recommend a monopod, if not a tripod. I use a tripod when I can.

When you crop the image of a full frame by 1.5, you reduce the pixel count to only 44.4% of the original. For crops/blow-ups, using a crop camera of 24 MP is like using a full frame of 54 MP.

I suspect the kit 18-135 lens is an EF-S lens, for crop cameras only. If Canon changed and now allows crop lenses on full frame mirrorless bodies, the camera will go into crop mode and eliminate the contribution of over 1/2 the sensor pixels. I went to the R7 to get all the mirrorless features in a crop body.

What makes you want a full frame?

NO! When we increase ISO most of us either reduce aperture or exposure time. This decreases S/N ratio.

After 42nd St changed hands it lost its good reputation.

As you can see, I have 2 pocket models, both Panasonic Lumix. The DMC-ZS100 is for the 1" sensor and I love it. I got it before the ZS200 came out. The DCZS80 is for the wide range zoom lens, and I love it too. Both have viewfinders which I insist on. Both are a little large for pocket use and require large pockets. I chose the ZS80 over the HX99 due to worries I'd break the 99's pop-up viewfinder. All have wider zoom ranges than the models with 25-75 or so lenses - I'm a fan of wide range zooms.

Good idea, take one.

I do not like to change lenses while on a shoot, so 70-200 or 300 plus a 24-70 doesn't work for me.
I compromised price vs zoom range and have a Sigma 18-300 mm zoom. Here is a used one for under $400:
https://www.bhphotovideo.com/c/product/802751343-USE/sigma_886306_18_300mm_f_3_5_6_3_dc_macro.html
Here is a better one: https://www.bhphotovideo.com/c/product/802871618-USE/sigma_886306_18_300mm_f_3_5_6_3_dc_macro.html

Nikon also makes an 18-300, but it is more expensive.

The Tamron 18-400 is heavier and more expensive, but with more range.

The difference in the systems is the sensor size, which has little to do with clarity. It hass more to do with cropping and overall size. The D7100 has an APS-C sensor which has a 1.5 crop factor, the OM 1 has a smaller micro 4/3 (MFT) sensor which has a 2.0 crop factor, making the result look like it was taken with a longer lens.

You can compare the two here (with a D7500 rather than D7100):
https://www.bhphotovideo.com/c/compare/OM+SYSTEM_OM-1_vs_Nikon_D7500/BHitems/1688415-REG_1333060-REG

It usually isn't the venue. It is the contracts with the performers who want royalties on their image, performance.