It should be part of Firefox, a feature to export and import bookmark branches. This extension fills that gap. Unfortunately, it breaks some times, without any warning, so we could try to fix it. Another problem is that it cannot export/import metadata (tags, dates etc.), and although that's a Firefox's internal problem, it does make the extension a lot less useful than it should be. In practice, it works just like copying and pasting bookmarks from the bookmark library (from a temporary profile), except that it can copy folders, too.

Apparently, the "tags", "keyword" and "lastModified" attribute are not exported to the JSON/HTML files because the Mozilla API is not making ALL bookmark attributes visible.

It seems that Mozilla is imposing their limited perspective of "legacy" fields and blocking access to those by either removing them from the Bookmarks API, or not making those available in the API, leaving you with only the option to export a FULL SET of Bookmarks, to JSON or HTML.

Because of that, the above fields that might have been used to keep passwords handy are not exported using the BM Porter add-on. It cannot access what is not m

That is truly unfortunate, because otherwise, the tool is PERFECT, giving the full desired control on which selected folders (and contents) are exported, as well as (extremely important) control over the target location where these JSON/HTML subsets are re-inserted into the overall BookMarks tree, which for me would be under the "Other Bookmarks" folder at the end of the tree, not merged into the "Bookmarks Menu" which is where other add-ons inconsiderately load them in.

Works exactly as described.

Just too risky for me, because I might lose those passwords (N.B. none of which are financial related :-) )

Tested on clean Firefox Esr 115 portable, FirefoxPortable 127.0.2 and 128, FirefoxPortableNightly_129.0a1. Everything's working fine. Deleted my last post as not credible
If you change in the Firefox settings: 'Choose how Firefox handles files downloaded from the Internet or applications used when browsing the Internet.' Specifically 'What should Firefox do with other files?' and instead of 'Save files', specify - 'Ask whether to open or save files' - then the Html file will not be saved. I set this item as default on my working Firefox and everything worked as it should. It's up to you to fix this bug or not, it's a small one.
In one running Firefox, I still had to change the 'handlers.json' file to a similar one that wasn't being used, otherwise the rollback didn't work. And exports, too

É uma extensão muito interessante, para se fazer a exportação ou importação dos favoritos, principalmente como backup de prevenção. Por favor, desenvolvedor traga o suporte desta extensão para o Firefox para o Android, pois o navegador para esta plataforma, não se pode fazer a exportação dos favoritos para um backup e muito menos uma importação se caso precisasse utilizar os favoritos de um backup salvo. Se adicionar o suporte vai ser fantástico.

atualização do meu comentário 11/08/2023

Que legal desenvolvedor, que grande notícia que a Mozilla trouxe, vou ficar no aguardo da extensão ficar compatível no Android.
Muito obrigado mesmo em me responder e até breve🤙.