Wifi mesh or powerline adaptors between router downstairs and desk upstairs.
Ergonomic mouse, ergonomic keyboard and external dual monitor.
a decent speaker – it’s much better to listen to music with bass in it.
Comfortable headset and webcam for any meetings.
a printer/ shredder
a standing desk that you can adjust electronically
Good lighting to avoid eye strain.
Lastly, a cup of decent coffee beside me. I would love to have a nice coffee machine behind me.
Feel free to share your gadgets.