Your wants are incompatible. You can have one or the other.

I figured that having a toe kick couldn't happen but I was hoping there was some way to make one that could be removed. oh well

Velcro or magnets could hold in the toe kick. I question the drain pan- most washer leaks are catastrophic- a hose bursts and you get hundreds of gallons coming out. This one holds five. How do you slide the machine in and out for servicing? Put the valves in an easily reachable location and turn them OFF all the time except when you do laundry. Or buy washer valves that do that for you (they only open when the machine is on)

Building cabinets in front of a washer and dryer is nearly always custom and expensive. Standard cabinets require the floor of the cabinet as part of the structure.

I can't get around the drain pan, that's happening. The pan has a fold down front panel so you can slide the machine in and then back out -- it's made for appliances that are under counters. It will be attached to a floor drain so hopefully that will help if there's a leak.

I think I have to give up on the toe kick idea. We have someone doing the countertop who does cabinet work as well, recommended by the cabinet dealer we use. If he's got a clever idea I'll let folks know.

(btw the water valves will be accessible but I do laundry all the time, so shutting them on and off isn't super practical. We do shut the water off when we leave for vacation or long weekends though)

If you have a fold down front how is that going to function in a flood , won’t it leak. Put a top over them both that lifts up for service and add a cabinet above . I just looked up the pan it needs to be riveted and then the rivets need removing to move the washer makes no sense to me.

A lot of folks seem to not like the idea of a drain pan under a washer. Isn't that necessary or at least strongly advisable for a 2nd floor laundry room?

The alternative is to tile the whole floor with a slope toward the drain.

I have no issue with using a drain pan. What I don't understand is why you think the toe kick under the cabinets has to be removable? I think standard toe kick size for a cabinet is like 3.5 inches. The washer/dryer won't be that tall. Just don't worry about it. And black will hide the pan underneath.

The shut off valves for the water will be accessible so I'm not worried about that. But I'm realizing that I cannot have cabinetry across the bottom (a toe kick). We considered re-doing the floor to be sloped with drain in center, but it's too expensive. The drain pan isn't all that expensive so it seems harmless, it's just not going to look good bc it's black and the machines are white.

Otherwise since these are commonly installed under counters, hopefully if we install with at least the minimum clearances above and to sides we should be ok. I hope!