Are there open source tools that can facilitate this? I see a lot of apps have this capability but seems pretty complex so I assume not all of them are building this from scratch (storing credentials, IP whitelisting, retries, refreshing data, etc.)
Even SaaS products would be nice too. It just seems like a huge undertaking and I'd rather not try and build it from scratch.
You can install the client on your machine and they install the client on their machine and you have a secure tunnel that lets you connect to their db just like that. There are other "zero trust" networking solutions that do the same, but Tailscale is refined and super-easy to use.