Quick summary: A lot of scanners now have native, open source support on Linux thanks to sane-airscan. (Details below.) 
I have a Brother MFC-L2750DW BW laser printer + color scanner combo. There’s an official Linux driver packaged in RPM and DEB, but it’s proprietary and places files in /opt/ so it’s not Silverblue compatible (even with the workarounds for some RPMs placing files in /opt/).
Until today, I haven’t had it working in Silverblue. I’ve had to use my personal laptop running “standard” Fedora 32 Workstation for scanning. (I could have set up some FTP scanning workaround thing, but I haven’t bothered.)
Thankfully, last night, I saw on Twitter that support for Apple AirScan (aka: eSCL) and Microsoft WS-Print (aka: WSD) is now available on Linux too. This means a ton of scanners will “just work” over the network. But we need support for it installed, as it hasn’t been merged into SANE quite yet.
To get my scanner working on Silverblue (and possibly yours too, if your scanner is supported), all you have to do is install an RPM (for now, as it’ll eventually be merged into SANE and then into Fedora, hopefully):
- Official code repo @ GitHub - alexpevzner/sane-airscan: Scanner Access Now Easy - universal driver for eSCL (Apple AirScan) and WSD
- Precompiled packages at the OBS @ Install package home:pzz / sane-airscan
- You can either:
- add it as a repo
- or just install the RPM (with
rpm-ostree install sane-airscan*rpmafter downloading it.)
- You can either:
I have this as an overlay on my own laptop, along with simple-scan (aka: GNOME’s “Document Scanner”) too (as it isn’t in a Flatpak anywhere yet).
Before overlaying sane-airscan and simple-scan, I did also test to see if this would work in a toolbox… and the good news is that it does work like that too! (Of course, this means you’d have to enter the toolbox and launch it from the terminal instead, unless you make a custom .desktop launcher with a toolbox run ... command.) This ia an option for those of you who don’t want to overlay it and/or don’t scan so often. 
TL;DR: Lots of networked scanners are supported by a new driver called sane-airscan. If your scanner isn’t working, or if you’re using a proprietary driver, see if it’s supported. It works well on Silverblue, thankfully!