The most common solutions for spindle/router for this class of machine across multiple brands is a Makita RT0700 series router or a clone like this one from Carbide 3D. Using this router as a basis and doing some conversion, the Makita is roughly comparable to a 1Kw (1000W) spindle in cutting power.
In the few instances on this forum where I’ve seen someone who has run both a Makita and a 500W spindle, they found the spindle to be underpowered by comparison, which tracks with the wattage estimates. The spindle still got the job done, but they had to use less depth of cut and/or federate in order to avoid chatter and other issues. I’ve not seen a 1000W spindle, but 800W spindles are common, and assuming the wattage rating is accurate, will likely give you a more comparable experience to a Makita router.
As for control, hooking up a relay to control on and off of a router is pretty common on this forum with multiple different solutions (IOT Relay, mechanical relay module, SSR…), so if that is all you want, no problem. If you want to control the speed as well, then that is more of an issue. Just looking at the pictures, most of the lower wattage spindles seemed to be controlled by a physical potentiometer (including the two you linked). Marlin outputs a PWM signal. I’m just a hobbyist with electronics, but if I was to solve this problem, I’d try using a cheap Arduino to take the PWM input and use that input to control a digital potentiometer.
If you go with yet bigger spindles (1.5Kw), then you will be dealing with a VFD. Controlling a VFD from a Marlin control board can (and has) been done, but there is a bit of electronics that needs to be added to convert the (typically) 5V PWM signal from the Marlin control board to a 10V signal at the VFD.