Switch two Macs, two displays, shared Magic Keyboard/Mouse

Screen Sharing suggestion:

With BOTH Macs powered on, and connected to your home network, and the BIG Display connected to the First Mac, you can Screen-Share (the pixels) of the second Mac into a smaller or larger sized window on a display on the First Mac.

My practical Example:

I use an older MacBook Pro, running an older version of MacOS, to open my personal checkbook registers in Quicken. (That older Quicken version does not run under modern MacOS.) The resolution on the older MacBook Pro is set VERY high. So high that the tiny numbers are hard to read directly on the built-in display.

I then Screen-Share that entire screen to a Mac Pro with a 30-in Cinema Display, and everything is perfectly legible, because the destination window (with the same number of pixels) is much larger. The tiny pixels from the MacBook Pro produce larger legible numbers on the Mac Pro 30-in display.

When the primary mouse moves inside the Shared window, it can go anywhere and click on anything on the second computer. It can do anything on the second computer, including "live" software update, and it will typically reconnect after a Restart.

Screen sharing works in the case where the very slight update lag will not be an issue. Screen Sharing does NOT work acceptably well with Full Motion Video. The faster the connection between Macs, the less the refresh lag will be.

I use Gigabit Ethernet for both Macs (through my Router). This local traffic is always Routed locally, it never is sent onto the Internet. You can use Wi-Fi or a mix (one Wi-Fi, one Ethernet) if your connection is fast. You can try it out without having to buy expensive Hardware.

I don't know of any Thunderbolt Dock that can connect to two discrete computers and allow one or the other to use its multiple displays and peripherals. Maybe other Readers can think of a way to do that.

I don't see a way to accomplish everything on your wish list with any reasonable-cost hardware, so I am going to continue to share my divergent thoughts about what CAN be brought to bear to reduce the re-cabling somewhat. Perhaps Readers can consider these and other ways to reduce, if not completely eliminate, the re-cabling headache.

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Re-use a built-in display instead (or in addition)

There is no requirements to CLOSE the clamshell to operate with multiple displays-- the built-in display can be used as one of your displays. Especially when choosing Extended desktop, either computer's built-in display could be added to any side-edge of the Extended Desktop of your Apple Studio display. Alternatively, A MacBook could be opened on the bench under the main display.

MacBook Air M4 already features a display with MORE pixels than your Dell 2K display, admittedly packed much closely together and harder to read at full resolution of 2560 by 1664 in only a 13-in diagonal space. I freely admit that for legibility, many users are using Scaled Resolutions to set that "looks like" revolution to half that natural resolution.

An open MacBook also provides an Optional additional pointing device and keyboard that can be used (or ignored).

the Dell 2725D appears to be a 2K display at 2560 by 1440, capable of 10 bits/color and refresh rates up to 180 Hz

connectivity includes

DisplayPort 1.4

2x HDMI 2.1

for this application over DisplayPort, cables between devices need to be no longer than one meter in length.

HDMI cables need to be certified to at at least PREMIUM specs, but can be up to a dozen feet long without issue. Higher spec ULTRA cables are preferable in the long run, and are backward-compatible

it appear that at 10 bits/color, the bandwidth required is too much to fit into the same Thunderbolt cable bandwidth as your Apple display, but it appears possible that at 8 bits/color, you might be able to achieve 60 Hz refresh rate.

Punchline:

This suggests that at reduced refresh rates, a genuine ThunderBolt Docking station MIGHT be able to work (it's close to fitting) for these two displays, reducing the number of cables for displays to be swapped to one. The Dock's lead-in ThunderBolt cable would be limited to 0.5 meters, unless the Dock-maker has a longer CAPTIVE lead-in cable with higher specs, or you buy an ACTIVE Thunderbolt cable.

The current model of Apple Studio Display is a 5K display capable of 10 bits/color with Thunderbolt-3 (not Thunderbolt-5) input, only.

it ships with a pre-engineered extra-long Apple Thunderbolt cable of length one meter.

Standard ThunderBolt-3 cables for use with high-end displays are limited to 0.5 meters length between devices, unless the cable is a much more expensive ACTIVE cable (starts at US$125).

Running at 60 Hz, that display consumes 73 percent of the possible raw bandwidth available on that cable.

what sort of work do you do?

¿Does your work involve full motion Video or magazine-cover level of Photography?