v6.1-beta.0 is released with support for SOCKS proxies both in iOS (via TestFlight) and Android (via Github releases as direct APK download: https://github.com/simplex-chat/simplex-chat/releases/tag/v6.1.0-beta.0).

You can host your own SOCKS proxy (this one looks good: https://github.com/heiher/hev-socks5-server) or you can try ours, if you use preset servers (it won't allow connecting to any other servers directly, but you can still send messages to anybody who uses other servers):

Address: 139.162.173.97

Port: 443

Username: user

Password: YJHolWSzTfOny7es