The best way would be to replace one of the switches with a smart three-way switch and use a regular bulb. That would be fool-proof when guests come over.
I had this exact situation. For a couple years, I used a smart bulb and left the upstairs switch always on. The only time it got shut off accidentally was when the cleaning company was here. It's an easy flip back on, though. If you already have the smart bulb, try it this way for a while.
Then not too long ago I replaced the upstairs switch with a smart 3-way switch and went back to a dumb bulb. I'm good at home improvement stuff (builders license, etc) and electrical, but I never did get it working as a proper three way. The smart switch now controls the fixture (good), but the downstairs switch will turn it off but not on (bad), and it never turns off the power to the upstairs switch (good). It essentially works how it used to, so it hasn't been high on my priority list to fix it.
The cheapest solution that would leave you a switch, if you have a Lutron Pro 2 hub already in your setup (and if this isn’t a code violation), would be to hard wire the bulb, and replace the switches with Pico Remotes.
Not the cheapest solution, but the best in my book wold be to order Inovelli Blue or Red switches + 2 white. These can be set to Smart Bulb Mode which always provides power to the bulb, and then the paddle acts as a button that can be setup to act on the bulb.
If you have a Hue bridge and want to use a hue bulb, there's the Lutron Aurora dimmer switch. It fits over your existing paddle. Works for guests who can still use it as a switch. Actually, I think it can be paired directly with HE also, but I've always paired them with Hue.