Good news! A very smart Arch user by the name of ronincoder discovered a fix for the headphone jack. I worked with ronincoder to make a kernel patch [1] and our patch made it into the 5.7 kernel release! It was also applied to the 5.4 LTS kernel. I booted both 5.7.2 and 5.4.46 and the headphone jack audio is loud and clear. 
Does it work for you? It should if you have a Samsung Notebook 9 Pro NP930SBE-K01US or NP930MBE-K04US (ronincoder's is the former, mine is the latter). You can check your laptop model by running alsa_info.sh and looking at "Board Name". The Realtek ALC298 codec in the NP930SBE-K01US and NP930MBE-K04US identifies itself with "Subsystem Id" 0x144dc169 and 0x144dc176, respectively. If snd_hda_intel sees either of these ids it implements the fix.
What about the speakers? I reported the no-sound-on-internal-speakers issue on the kernel bugzilla [2]. Linux sound maintainer Jaroslav Kysela speculates that there may be some amplifiers connected to the HDA codec which are not initialized by the BIOS, and are thus not active in Linux. He suggests dumping the codec communication for the Windows driver using QEMU. We could then parse the dump and replay the communication in Linux using Early Patching [3] or writing another kernel patch. It's been a month since Jaroslav made this suggestion and I've made some progress but I still don't have a good dump. Please join the discussion on the kernel bugzilla if you'd like to help me. ^^
[1] For reference, our patch made it into Linus' tree as commit 14425f1f521f (ALSA: hda/realtek: Add quirk for Samsung Notebook).
[2] https://bugzilla.kernel.org/show_bug.cgi?id=207423
[3] https://www.kernel.org/doc/html/v4.17/sound/hd-audio/notes.html#early-patching
Does it work for you? It should if you have a Samsung Notebook 9 Pro NP930SBE-K01US or NP930MBE-K04US (ronincoder's is the former, mine is the latter). You can check your laptop model by running alsa_info.sh and looking at "Board Name". The Realtek ALC298 codec in the NP930SBE-K01US and NP930MBE-K04US identifies itself with "Subsystem Id" 0x144dc169 and 0x144dc176, respectively. If snd_hda_intel sees either of these ids it implements the fix.
What about the speakers? I reported the no-sound-on-internal-speakers issue on the kernel bugzilla [2]. Linux sound maintainer Jaroslav Kysela speculates that there may be some amplifiers connected to the HDA codec which are not initialized by the BIOS, and are thus not active in Linux. He suggests dumping the codec communication for the Windows driver using QEMU. We could then parse the dump and replay the communication in Linux using Early Patching [3] or writing another kernel patch. It's been a month since Jaroslav made this suggestion and I've made some progress but I still don't have a good dump. Please join the discussion on the kernel bugzilla if you'd like to help me. ^^
[1] For reference, our patch made it into Linus' tree as commit 14425f1f521f (ALSA: hda/realtek: Add quirk for Samsung Notebook).
[2] https://bugzilla.kernel.org/show_bug.cgi?id=207423
[3] https://www.kernel.org/doc/html/v4.17/sound/hd-audio/notes.html#early-patching
