Thunderbolt 2 -> Thunderbolt 3/4

MY CURRENT (AGING) HARDWARE:
late-2013 Core i5 iMac, 21.5-inch; 1 TB HDD, 8 GB RAM
currently running MacOS 10.12.6 Sierra, about to clean-install 10.14 Mojave
favorite apps: Office 365, Apple Mail, Safari, FireFox, Chrome, iPhoto, DymoLabel
occasional apps: Final Cut Pro 7, iWeb, Quicken, EpsonScan, etc.

I used to run Adobe Creative Cloud; my ACC subscription was cancelled at the end of a sponsorship for a long-term business project. I am now seeking a new avenue to secure a renewed ACC subscription. I got light-to-moderate use out of Acrobat Pro, InDesign, Illustrator and Photoshop. I want to expand my use of ACC both in terms of how many apps I use and how much skill I have in each.

My aging iMac is obviously wayyyyy out of date. I am still getting lots of miles out of this budget workhorse.

My reason for posting this here today: I am seriously thinking of spending some reserve money to get at least one new or refurbished Apple Silicon-equipped Macintosh computer. Top candidate, at least to start with, would be a Mac Mini. If I bought a Mac Mini **right now** (very tempting), I would get it with 16 GB of RAM and probably ample built-in SSD. It would easily be at least $1,300, not including a Logitech keyboard, mouse and Apple trackpad.

Here's where things get weird:

While I intend to eventually get an external monitor for the new machine, I won't have the budget for it right away. Extra funds, if available, would like go to a new ACC subscription. The solution? iMacs of that vintage have a little-know feature called "Target Display Mode" (TDM), which allows the iMac to be restarted as an external monitor. For the near term, assuming I "push the button" and buy a Mini, I would plug it into the iMac in TDM. Thus, the old iMac would do double-duty as the Mini's external monitor.

Screwy solution, I know, but it should work for the near-term. It's the best way to actually make a commitment to the new silicon and all the current software that runs on it.

Here's where things get weirder...

The old iMac has ThunderBolt 2. The Mini, as with other late-model Apple Silicon computers, uses ThunderBolt 3 / 4. Is there a straight, high-quality cable on the market right now with ThunderBolt 2 male on one end and ThunderBolt 3+ male on the other end? I see Apple has an adaptor dongle, But I want to see if there are any good aftermarket hybrid cables out there. Any suggestions?