Proper desktop GPU as eGPU, always cheaper and faster (and cooler and quieter) than a gaming laptop with its dGPU. eGPU is losing only in games in the amount of max fps it can push, it can't go past 200 in most games with fully maxed graphic settings (big deal 🙄), in basically everything productivity/work-related it is faster.
What A has said, to get a cheaper laptop with weaker dGPU (or without any) but strong CPU, with eGPU is going to wipe any single existing gaming laptop in any GPU-heavy workload always - for less money.
For example, currently the cheapest (in the EU) 4080 laptop is this MSI for 2200€:
https://www.computeruniverse.net/en/p/GWLF-953For 1800€ you get a desktop 4090 with 8 GB more VRAM:
https://www.computeruniverse.net/en/p/2E07-575You get any decent eGPU enclosure for 250€ on average and save 150€.
4090 desktop is almost twice faster (80%) than 4080 laptop. With generous 25% bandwidth loss over Thunderbolt it is still much faster - still for less money. And yes there's a cost to buy a laptop but you get effectively two dGPUs, one in an eGPU enclosure for home and one weaker when you need it on the go (one certainly won't work on the go on battery with 4080 or 4090, unless they want to work 40 minutes). Plus the fact that performance per €/$ is going to be better and the fact that in future it's possible to simply just upgrade a GPU (good luck with that in the laptop).
If you get a 4080 desktop it is still going to faster than a 4080 laptop for even less money, enough difference to buy a decent new laptop for cheap.