A wood reducer to match your flooring should work nicely. If no one has one, they should be able to make one out of wood stock to match. It might cost a couple of bucks, but it shouldn't be too too astronomical.

I'm not sure I'm reading this right, but does the slate-look vinyl need a transition to hardwood flooring? Then why not use a reducer made of wood, stained either like your hardwood-floor room... or even with an oil-based stain like miniwax "ebony" that mightlook good against a black slate-look vinyl floor? You can always just buy the reducer wood strip and stain it, lay it there after it cures to see how it looks, walk around to see if you like it before committing to it fully by fastening it down. Btw, I hate metal strips too and would only use them (if forced to!) to transition to a fully carpeted room.

I have hardwoods in the kitchen and also in my master bath. When I was researching about putting them in the bath (worried about water issues), I was convinced by people on some forums here, that regardless of the flooring, if you have a serious leak or flooding, it's going to ruin whatever floor you have. Or at least it's going to have to be pulled out in order to avoid mold and underlayment issues. So, I wouldn't have any worries about using wood in your kitchen, esp site finished oak. It will stand up to anything, barring a serious leak or flood. I understand your desire for a dark floor "However, the kitchen look that I love is a marble type quartz countertop, with a dark brown floor" but since you are expecting to sell soon, I would think a cohesive, coordinated floor throughout the house, will appeal to more people than the look you want (when it's so different from the rest of the house). Maybe you can make your preferred look, the look you want for this kitchen, your goal for the house you'll be buying to replace this one?

I did both. I was taught by an installer how to flush cut the flooring to butt up against the tile, which did have an edge strip, with a 1/16th (I think, it’s been almost 2 years) gap and silicone caulk. I hated it because the flooring is matte and I couldn’t find a caulk that wasn’t shiny so it left an obvious shiny line between the tile and the laminate flooring. I replaced it with a transition strip. I do remember messing with the strip to making it as flush as possible between the two different floorings, I think we had to modify the metal piece inside or route one side deeper. keep in mind all of this was DIY and with proper planning by a pro installer the different floor levels are taken into account. I changed my mind and decided to tile the powder room when the flooring was already in. Also, in this scenario the ends are supposed to be sealed and caulked beneath the transition strip in a powder room application, even if it isn’t “wet,” like with a shower or bathtub. That was so deep in the specifications for the flooring we almost missed it. I did not use a transition strip by the front door. I intended to, just to be cautious since we spanned a greater distance, but I hated how the strip looked. Next to the threshold the caulk is invisible, even though it’s shiny. We were pressed on time and budget because it was a new home without any closet shelves, garage storage, or landscaping. The idea of replacing the carpet that was falling apart (after less than a year) with more of the same carpet by the builder was discouraging to me, so we really couldn’t do anything differently. But in a more predictable world, if I could have wrangled a couple thousand more, I have done a simple, not engineered, hardwood and installed it ourselves. The laminate has not had any issues at all as far as buckling or drifting. It’s on our main floor and the only place with an issue is where my kids drop ice cubes on the floor in the same spot and don’t pick them up. There isn’t any swelling or peeling but there is a thin line where you can see the composite is a different color. This is not in an area with a long span. The LVP with equivalent numbers of pieces were 2-3 times as expensive.