> A bell is still rude in a shared space

I just don't think that is even a little bit true, or at least it's something that is very culturally specific and thus not generally applicable.

I have a friendly sounding bell I use from an appropriate distance (and I can modulate the volume), and I routinely have people give a light wave to show they heard. In addition, the biggest complaint about cyclists in local social media is about them passing without notice.