I am very surprised how few people have voted for this here.

As far as I know, no. At least I did not find it when I was working on the character counter.

The conversation about this on TJC got a lot of attention recently. Though most of it was just people yelling at each other, juiceme and another person came up with some pretty good insights. Are we any closer to getting a working solution? I would love to help in any way I can (testing, money, etc).

I don't think anyone is working on it really. The problem with making a lot of noise on TJC is that people on TJC are mostly users with no developer background, hence there are bound to be a lot of misunderstanding

People on TJS would like Jolla to fix this in the sailfish messaging application but as I see it it is easiest to do the thing by creating an alternate messaging application to replace the implementation; After all that's how it is done in android too, there are countless alternativa messaging applications in play store...

It looks to me the thing itself is not that difficult to implement; it just needs a messaging application that can extract the user list from message header part and do the multiple sending. Something that could be whipped up is a few days.

So here is easy pickings to some aspiring developer who wants to have recognition, seems some people really do need this

...the kind of people who like making a lot of noise

(Which, incidentally, is why I am no longer visiting TJC.)