Overlay network with constant addresses?

[yeti]

I'm looking for a replacement for Tor's hidden services. My services do not use Tor to hide, they just need that constant address that is independent of my location, physical address, internet provider, DNS provider, ... the strong privacy of Tor is far more than I need there.

When ARTI will be the new Tor, I will drop it. I'm not in the mood for Rust.

So I'm looking for such a similar overlay network with *.onion like constant addresses, that should be well defined (RFC? Spec?) and be implementable in lots of everyday languages that don't need gigabytes of toolchains.

After some experiments, I2P's C++ implementation looks like a bigger CPU hog than Tor even when only idling. If that may be local config PEBCAK, I'd give it a second chance.

But are there other overlay networks I should look at?

It should be "open". E.g. needing a keypair for each connection contradicts my wish list.