Of the listed applications, which one will first hit 1 megawatt of electricity usage?

Beamed power: traditional solar power satellite concept. Solar cells in orbit, on-orbit power conversion, and transmission to some other customer (on Earth, on the Moon, whatever). Presumably microwave transmission, but could be optical or otherwise.

Reflected sunlight: what Reflect Orbital is trying to do. Mirrors in space, solar cells on the ground. Measured by electrical output at the solar cells, not sunlight power.

Hosted data center: computers in space, using space based power, for computation. Not including comsats or computation solely in support of those. Could be servers for rent, or for a specific fixed customer, but some sort of general-purpose computation, like CPUs or GPUs.

Cryptocurrency mining: Bitcoin or otherwise. Like in-space data centers but special-purpose compute.

Manufacturing: any physical manufacturing or mining, whether the products are for in-space use or on-Earth use. What Varda is up to.

For all the categories, the power collection has to be in space. Solar power on Mars not included (though Mars orbit is fine as well). In all cases the electricity usage is being counted. If a satellite is multi-purpose (the ISS, for example), it will only be included if application-specific power budgets are available. Application-specific satellites will count their overall power budget.

All cases are steady state, not peak pulsed power, though there's not specific duty cycle requirement.

Total consumption across all spacecraft.