Steam Machine purchase - worth it?

Hey everyone! I've seen the steam machine launch and I'm thinking about buying it, but want to ask if there are alternatives that would make a better setup for me.

The situation: I built my desktop PC in late 2020, and have upgraded a couple parts since then but it's starting to become less and less usable with newer games. As well as this, I have a Steam Deck plugged into my TV that I use for couch gaming (which is also starting to feel slow with newer titles, the new LEGO Batman I'm barely breaking 40 fps)

With the launch of the Steam Machine, my plan would be to replace my Steam Deck with it so I can play games at 1080p with more stability in my living room than I currently can, and occasionally use my PC for more intensive stuff when needed. However, I was wondering if it would be worth investing in upgrades in my desktop and streaming my Steam library from it to my Deck instead? If so, what upgrades would you recommend over the cost of buying a Steam Machine outright? (Based in the UK, price is £879)

Desktop specs:

CPU: AMD Ryzen 7 5800x3D

Mobo: Gigabyte B450M DS3H

RAM: 2 x 8 GB DDR4-3600 CL18

GPU: Gigabyte OC RTX 2060 6GB

PSU: Corsair TX750M Gold

Thank you!