There is a big difference between a real surround system and a soundbar, even a cheap surround system. I would do what you have to do to keep it. I’ll be honest, I’m not sure I understand the eARC issue. The last time I upgraded our TVs… suddenly all the TVs and surround systems and sound bars suddenly started working together under the eARC input. I only had to upgrade my HDMI cable to 2.0 or something like that.
But I understand. My partner is disabled and bedridden, so we have a 65” and a soundbar in the bedroom. I think it is pretty easy to show ~ best is the Sennheiser Ambeo. Add a small sub and you have really good natural sound, but not surround.