What you are looking at, for some more advanced package(s) (within stable distro), in order to get necessary (latest) dependencies, is provided within sid main (you know that already, but as we need to stay focused on installing one particular package, I cannot skip what needs to stay within frame of logical thinking, what achievable and what not). For example, approach to install Librewolf changed slightly while its official repo exists as well, some other repositories available too, but, to install (just remember not to use upgrade in such case, never ever) librewolf_108.0-2_amd64.deb you might reuse this reliable guide: Making Wi-Fi 6 AX201 work in PureOS - #5 by Quarnero.
Hope that above helps, it is your turn now (as requested), especially if @mladen do not mind (as this install approach/guide belongs to your local PureOS system, the one that you want to preserve control of).
@zlg, there exists another package(s) for which the very same rules on how to apply them … please check your PM, but before you open it please check this, up to your question closely related, post: Fully Free PureOS Alternatives With Newer Software - #3 by amosbatto. Thanks for asking, as current Debian “options” provide all necessary, up to your precise question related, I’m quite sure!