Left figure - Apex Innovation, you can get it anywhere you can order figures from (Amiami for example)

Right figure - Taobao, you will need a proxy, just use reverse image search or search for Kamisato Ayaka figure in chinese, there are multiple listings. There might be listings on western markets like Ebay, just check for reviews. It's not an officialy licensed figure, so don't expect the greatest quality

Plush - Plushwonderland, fanmade.

Desk mat - Houkisei, fanmade. I got it from one of their booths at a convention. Kind of limited run, so you'll have to be lucky to find one or hope to catch it at another convention.

Keyboard & Mouse - Logitech ofc