While feature creep is indeed a problem to manage in any software project. The wedding of intrinsically similar tools has a great many proponents, myself included, on the basis that the incremental work and weight is far less than the net work and weight of two separate projects that share many core ideals.
And as LastPass clearly felt when it bought and integrated Xmarks these two ideas are closely related. Mutliple platforms, multliple browsers, store URLs, store some extra data. The password manager needs a few special tools, like form fillng and random password generation. The bookmark manager needs a special tool - mapping client bookmarks to the data store. The rest is shared.
Be that as it may, it is subjective will always have jeremiah’s voting one way and Bernd’s the other way, and that is fine. The job of product management if anyone has it individually or as a team is to balance those voices.
Given the code for the leading browsers (Firefox and Chrome) is in place in two FOSS projects already and yes, not write-it-in-your-sleep trivial, also not herculean, just a mapping of a client’s API to a remote API in a sense with the quirks of two leading browsers well understood already it seems.
Anyhow, feel free to object. But in the mean time some of us hope to gather more upvotes for this baby ;-)… Not a rush mind (I’m using floccus on Nextcloud now and it’s fine, just another app, another add-on and other toolbar icon and so on, when the two ideas are closely related).