Since remastered versions of DS9 and VOY aren't happening any time soon, I think the next best thing should be a SD-BD release, kinda like how Discotek Media are doing with some old anime titles
Hey, there was an article a little while ago about some fans who were using AI to upscale the old episodes. Either those fans or people like them succeeded in their task and you can find their work freely available if you know where to look.