Converting old photos to JPEGs in Lightroom?

This is a question about photo management in Lightroom Classic – I pretty much know what I’d like to achieve, but I’m bit uneasy to experiment, knowing how flimsy and buggy LR can be. As such, I’m eager to hear from people with first-hand experience in similar operations.

I use a single catalogue, ~30k photos, ~300GB on disk. I’ve noticed recently that I primarily operate on last 2-3y worth of photos, not touching older photos. As such, it’d make sense to "flatten" those older photos to JPEGs; I’d save some disk space and make it easier for myself to browse the photos across different devices (DNGs are routinely rendered in a weird manner the moment I step outside of my win10 ecosystem :). I’d prefer to stick to single catalogue for my photos. Is there a sensible way of converting the photos "in place", preserving all of the metadata the original photos have? The edit history would obviously be lost, but I’m okay with that. If that kind of process is relatively bug-free, I could imagine yearly move of the cut-off point, to ditch RAWs from yet another year.

Anyone doing something like that? Any gotchas or ways you’ve seen this explode?