What is missing:

-system should remember tiles position on exit (even when active tiles are mixed with empty ones) and should not automatically rearrange tiles when one is dragged to new empty place (former place of relocated tile here should be replaced with [+] empty one; tile while dragged can look like dotted line contour, OR tiles can be dragged as they are with just empty space left on their former place (further click on such empty space should add new tile))
-search engine change (otherwise that may look as a kind of pay-per-click referral stuff) and option to hide search form section since it takes pretty much space
-'colour tiles' potentially is a good option, but without possibility to set own colors it does just a half of job: with manual color set it would allow user to visually separate tiles by groups
-when last available tile is used, new [+] empty tile may appear (just optional may be)

Everything else IMO is good as it should be. Neat, lighweight, well-balanced add-on comparing to others. Just few key things to improve.

Will update comments/rating when anything from above is changed.

Good but...
- I can't change the "Preview" manually (eg; I don't want to have a RGPD or cookie information in this preview)
- Why some history appear on the menu ?!? no button for disable that?
- When I drag some element I need to reorganize approxymately all
- Need each time to go on "configuration menu" for add new tiles...
- When I have only 3/4 colunm, the height is so crazy why I can't change the height or create button for auto height?
- Backup config?!? if I want to use this config in another browser?
- Why startxxl in "default search engine" when I use duckduckgo and I can't change...

And I think that's all, the rest is good, contact me if you need some other information
I edit this post if needed

back to being very good, thank you:)

On the floor of the setup menu screen. Impossible to remove.

Es gelingt mir bisher nicht Speeddial als Startbildschirm zuinstallieren damit ich auf dem Tablet genauso wie auf dem PC die Bookmarks auswählen und aufrufen kann. Auch nicht wenn ich in den Einstellungen/Startbildschirm den Link von Speeddial reinkopiere.

Endlich gibt es einen vernünftigen Ersatz für das alte Speed Dial.

how use firefox bookmarks?

It's a really good replacement for the outdated old "Speed Dial" add-on. Nice backgrounds.