Gmail offers imap amd smtp access. You have to enable 2FA, and then it will allow you to create account for so called “less secure apps”.

In your place, I’d either continue using gmail directly, or finish the configuration of the self hosted mail server and just use that with any smtp/imap client. I suggest getting a separate domain for testing first, before moving your primary inbox there.

you still need good security configuration of the exposed service.

In a sense that security comes in layers, yes. But in practice, this setup will prevent 100% of bots scanning the internet for exposed services, and absolute majority of possible targeted attacks as well. It’s like using any other 3rd party VPN, except there’s not a central point for the traffic to flow through.

From the attackers point of view, nothing is listening there.

I’ve used a similar setup in the past to access a device behind a NAT (possibly multiple NATs) and a dynamic IPv4. Looking back, that ISP was a pure nightmare.

This is not a guide to hide from the government or ISP. Just a way to tunnel to your home server without publishing the sshd for random strangers. Personally, I’d just publish the ssh and be done with it.

I would rather live without the correlation attacks

The more people using Tor, the less useful targeted disconnects become.

Which is still just as open, but also a massive calling card for anyone trolling around the TOR network

Luckily, it is no longer possible to easily sniff the new v3 addresses by deploying a malicious relay. Any attack to even reveal the existence of a hidden service would require a very specialized setup. And we’re just talking discovery, not the ability to connect and attack the actual service running there.

just connecting to Tor is very much a huge exposure imho

Exposure of what, to whom?