As far as I know the Galaxy Tab S2 8.0 Wi-Fi is the only Tablet supported with 8" display, but without LTE support. However it is not any more supported and latest version is Pie dev 0.23 for April 2022.
There are couple of unsupported tablets with unofficial build which might meet your requirements, but with old eOS versions:
There is a lack of 8" tablets for LineageOS / eOS at the moment unfortunately. I dont think there are many Android 8" tablets any more on the marked. I just could found those 2 tablets which having a quick search:
Galaxy Tab A7 Lite LTE
Lenovo Tab M8
Maybe the are supported by LineageOS / eOS in the future