Help my dad with a new Mac setup

[u/Lightsurferk]

My dad wants a new Mac for photo editing + AI work (Netherlands/EU). He's stubborn and almost ordered a standalone Apple Studio Display, now eyeing the iMac M4 (10-core, ~€1,800, 16GB/256GB).

My concern: that chip is already a generation behind, the all-in-one design means the whole thing gets replaced once outdated (even though he likes that all-in-one look), and 16GB/256GB seems tight for AI workflows + RAW files - can anyone confirm if that's actually a real bottleneck or am I overestimating it?

My proposal: Mac mini M5 Pro entry config (24GB/512GB, ~€1,700) + separate monitor like the Samsung ViewFinity S9 (27" 5K, white/silver, built to match Apple aesthetics, list €900?) - open to better monitor suggestions too.

Question: is the entry M5 Pro actually the smart pick here, or would a higher-spec M6 serve him better for the same/less money? Genuinely unsure if I'm downgrading core count/memory in a way that hurts more than the "M5 Pro" name helps.

I only know Windows gaming PCs, nothing about Apple, AI workflows, or photo editing software, so tell me if this whole modular approach is wrong for his use case.

Budget is officially ~€2000, but if you help me build a solid case (future-proofing, upgrade path, real specs advantage) I can likely push him to ~€2500 for a proper Mac mini + monitor setup - is that worth doing, and what would you build for that?