Projector upgrade - 4k?

Hi there, I currently have an Apeman m4 DLP projector, which according to the specs has:

• anywhere between 480p and 1080p ("supported" so I assume 480p it is).
• 50 ANSI Lumen

Id post a link but not sure if that's allowed in this sub.

Anyways, I am looking to upgrade, because I've had this thing for 3 years now and its time to step up a bit. To be honest, given that I only watch when its dark outside, the brightness was pretty much okay so far.

However, the resolution is obviously bad.

Long story short: for indoor use, about 3-4m viewing distance from the screen, is it really worth it to spend the extra money to get 4k, or should 2k be enough?

Looking forward to your advice!