[jedisct1]

dnscrypt-proxy also supports DNS-over-HTTPS and is probably the most popular DoH client.

You can use it to connect to Cloudflare or other DoH servers, and this will not be limited to queries sent by Firefox.

On iOS, use DNSCloak.

[rajadigopula]

AdGuard app on android also allows dnscrypt to route all the phone communications go through the dns crypt servers encrypted without rooting.