HF radio+antenna and digital setup. Digital setup includes computer (or a rpi), audio interface to your radio and (optional) cat control to radio.
for example i have a ft-891 with a usb 2.0 type-b to type-a for cat control (lets the software set frequency of the radio), and then a mini-din connector that connects to the back of the radio and gives me a mic/speaker connector which i connect to a usb sound card into my rpi or computer. then you can use js8call or WSJT-X (for other modes like ft8).
you will probably want at least a general license. since tech doesn't give you a lot of hf access, but since this is digital (can be same allocations as CW) you can do some on tech license.
The sad thing is that MPI-3 doesn't have wide acceptance yet. A lot of organizations mainly use MPI-1/2. While using RHEL 6.x. Shoutout to red hat for maintaining ancient software