I tried using my RasPi3 as a stand alone box for a few days, but it was too feeble.
It's not an SBC, but I'm currently running a Chuwi LarkBox Pro for the last 2 weeks.
Chuwi LarkBox Pro Stats: Intel Celeron J4125 CPU @ 2.00GHz × 4 mem 5.6 GiB Intel Corporation UHD Graphics 605 Linux Mint 20.1 Cinnamon ver 4.8.6 kernal 5.4.0-65-generic Win10 dual boot, but only use Win for a video chat app that isn't ported to Linux.
Yeah, I needed a usb hub with a NIC, but it works just fine.
It's been working without troubles for basic email, web surfing, text editing, spreadsheet, etc., handles 25+ tabs in Firefox, video plays fine, I have no need for 4k content.
It's likely not up to tasks like video editing, but audio editing on Audacity is great.
Can't beat the price if one is on a strict budget like I am.
SBC's keep getting more powerful, so soon they'll be ready for a single box replacement, some good looking boards coming out these days.