Earlier quoted context omitted.
DoH and similar technologies don't override /etc/hosts. They're just a different way of making DNS queries. The entire point of these technologies is to prevent your ISP and everyone else along the way from knowing which websites you visit.
DoH means that each application does its own DNS queries, instead of using the OS's functionality. Whether that includes reading /etc/hosts is up to the application, and it looks like high profile applications like Chrome and Firefox don't read /etc/hosts. > The entire point of these technologies is to prevent your ISP and everyone else along the way from knowing which websites you visit. More correctly, the point is…
HUH?! No! You aren't supposed to implement DNS on the application level! Most modern OSes support some form of DNS over TLS at the system level. You should use that.