I really want to use Firefox, but feels a bit odd

Don't get me wrong, I like Firefox a lot, but needs polishing.

I like -impopular opinion- the Proton UI (aka rounded tabs), containers are great, but has some flaws:

• No PWA support
• Bookmarks and history panels are unpractical (menus for both options are almost unusable)
• A separate window for downloads, managing bookmarks? Really?
• Pocket by default?

We need alternatives to Chromium, and Firefox is the "go to" option, but sometimes is disappointing to use it.