I would not recommend you going full iPad without a proper computer. There has been a lot of advances on the platform, and it can pass by a computer for day-to-day use. But for professional use, it is not as good. May programs are not available in iPadOS and are available in MacOS in a usable way. You will also have to buy apple's stand with built-in keyboard and trackpad to make it usable, unfortunately. If you already have a good drawing tablet, you might be better off spending your money on a computer like a laptop or desktop.
You would likely not be able to keep the computer working this long well enough for work if you were rocking a 2009 MacBook. iMac gives you more performance, but the base iMac will cost you more than the base MacBook because it's more powerful. But if you compare similar specs, iMacs are less expensive. If you don't plan to work outside of home, you might be better off with an iMac, but the starting price is higher. there are no refurbished iMacs in the store.
In conclusion, if you can get a 16Gb MacBook, you should be ready to go. But it will still be more expensive than getting a mac mini and a monitor.
Buying a 6 core i5 mac mini (with slightly worse graphics card but shouldn't make a difference) plus a monitor should cost you 1180US.
Originally released March 20208GB of 2666MHz DDR4 SO-DIMM memory512GB PCIe-based SSD1Four Thunderbolt 3 ports (up to 40 Gbps)Intel UHD Graphics 630Gigabit Ethernet port
www.apple.com
Philips 278E1A 27" frameless monitor (E Line) Simply stunning The 27" E Line monitor features stunning visuals and elegant design for a stylish enhancement to your workspace Ultra-clear 4K UHD with wide-view delivers same ultimate clarity and life-like visuals from any front angle view UltraClear...
www.amazon.com
And that's including a professional level screen which is 4k and 27", much better than the macbook's retina (and much bigger as well). You can also by more ram and install it yourself quite easily for less than 70 bucks
UNBUFFERED 16-16-16-39
www.amazon.com
Making the total less than 1250US. Which is 20 bucks less than the MacBook. For professional work. I would recommend that. Will be usable for longer and gives you more flexibility, once chances of it getting damaged during time (you will drop the laptop way more likely than a standalone screen) are slimmer and upgrades are easier and cheaper. It will also use about as much space in the desk, maybe a bit more because the screen is bigger: The mac mini can be out of the way, and keyboard in front of the screen as well as a drawing tablet.
You will still have to buy a keyboard and mouse, but they can be pretty cheap. You don't need to buy them from apple as there are excellent options for about the same price or... half the price, really. Less actually. You could buy a mechanical keyboard with the money for a magic keyboard. And a mechanical one is lighting years better for fast typing, games, and longevity... pretty much everything.