It’s a great question. I am missing certain content from the niche sub-reddits and trying hard not to fall back to Reddit.
Some of this ‘reposting’ will help the community to add comments/interaction but as you mention may turn this platform into a leech.
Either way people implementing Bots helps the moderation teams to some extent.
A Thunderbolt cable will handle the required bandwidth from the dock to the laptop.
Your phone, do you expect to pass data via the phone and your laptop (eg photos/videos?) If you do then a USB 3.2 10 Gbps cable would be the most you would need (€25), costs may stear you towards a simple charging cable something around 60w (€10) would be ample BUT you phone may not fast charge due to Samsung’s charging preference.
HDMI 2.1 would be ample for a your monitor (4k resolution at 120fps) and the cost difference between this (€13) and 2.0 (€10) is minimal nowerdays
Ethernet is easy, CAT5e in the colour/length of your choice would supply the potential max 2.5gb Ethernet port you have (€8 for 10meters). Higher the CAT rating the more costly the cable.
Additional Thunderbolt ports would be best used/reserved for high-speed external storage or even a gaming GPU.
The fact your asking about these items shows you should be pretty much covered for the next few years of ‘fitire proofing’