Numerous 802.11ac-ready 5GHz-capable USB WiFi adapters are on the market.
This article explains how to configure an Ubuntu Linux system to perform double duty with the hostapd package as a Wireless Access Point to allow, allowing other devices to connect to the web through the PC.
That PC must have a separate WiFi or Ethernet connection to an Internet-connected router or gateway.
RuleSuggest you rule out all Tp-Link USB devices, as per a chat with TpTP-Link chat support agent Rikka @ 08:33 on 2020-04-17. they don't support WAP configuration.