Hate to break it to you, but from what I've read your Grand Wega might be HD compatible, but you're not getting a true HD picture, even with the DVI cable.
If you're not willing to part with the TV, then that's on you. It's had a good life, let it R.I.P.. It's a 16 year old model, and there's PLENTY of better, higher resolution TV's available for probably 80% cheaper than what you paid for your Sony. I get it, CRT (and plasmas) screens are great, but if they're a pain to get working with modern tech, it might be time to move on.
Yeah, I got some Rokus.
https://youtu.be/d1CSEeqWl10