If you're switching from a github alpha (debug) version, this version will install side-by-side with your current version, so there should be no risk of data loss. However, it's always good to backup your settings, layout, icons, and wallpaper anyway, and this will also let you restore these things in the Play Store version.
To create a backup of you current Lawnchair settings:
Open the "Home settings" by long-pressing anywhere in the blank space between icons on your home screen and choosing "Home settings".
Use the three-dot menu in the upper right to choose Create Backup. Save the file somewhere handy.
Later, restore that backup in the new version of Lawnchair.
It's weird having both versions installed. When I open my app drawer and search for Lawnchair, I only get one result, and now that I've restored my backup, I can't even tell which version is being launched when I tap that icon. Thankfully the alpha version is named "Lawnchair (Debug)" in the Apps list, and I can now uninstall the debug version.
As someone who used Nova for ... shit, feels like a decade, I was also concerned about this when switching (I heard Nova was sold to an ad company and was super sketchy) but after using Niagara Launcher for the past month, I realized Nova was more complex than I ever needed. I haven't tried Lawnchair yet, but don't be afraid of switching unless there's a hyper-specific feature you can't live without. Give another launcher a shot for a week and see if you're really missing Nova still!
I was on nova too. I tried a couple of launchers and settled on lawnchair. I like that it doesn't try and force a new way to interact with your icons and screens.
It hasn't the amount of flexibility of Nova, but I really didn't need all that, I just want a nice stable launcher I can set up and forget.
I tried it the other night on my Pixel (Android 15) and had no issues. I've been trying out different launchers in an attempt to find one which isn't asking for a monthly or yearly sub and has horizontal app drawer as an option! Both of which are getting to be more rare these days. I couldn't see where to make the drawer scrollable on Lawnchair, so I skipped it for now.