A note from a Solus forum discussion on Edge-Linux last night:
"[I am] completely perplexed why such a basic function as importing bookmarks wasn't available when I tried to help my roommate use the feature a week or two ago. Whenever he clicked on the settings page to import his bookmarks the page was completely blank."
I checked last night (using Solus 4.2 Budgie and Ubuntu 20.10) and the Solus forum post is correct. Import isn't available on Edge-Linux, either through "Settings>Profiles>Import Browser Data" or "Favorites>Settings>Import Favorites". In both cases, the user gets a blank screen (edge://settings/ImportData) that locks.
The odd thing about this is that I remember importing favorites from an Edge-generated HTML file when I first installed Edge-Linux in late October, then removing the imported bookmarks before syncing when MSA sign-in and sync became available a few weeks ago. So import seems to have been working before it stopped working. Its possible that my memory is faulty, but I found another discussion on this forum** that indicated that import stopped working on Edge-Linux after 90.0.818.6 was released (March 9).
I confirmed the bug to the Solus forum last night. I've reported via Feedback with the error logs, obviously, but does anyone have information about this issue (what is hanging up import and/or plans/timetable for resolution) that I can report to the Solus forum? Edge-Linux is pretty useless for new Linux adopters if bookmarks/favorites can't be imported.
** See "Importar favoritos parou de funcionar", March 15. See also "TypeError when importing favorites on Microsoft Edge 91.0.825.0 dev", March 19, if you would like to see a typical error log.