At least to me one of the challenges is relating to the problems that BGP solves. You can get pretty far in network complexity before BGP (or OSPF etc) really does anything for you. What would be good scenarios one could encounter in "homelab" situation where BGP would be beneficial?
There are no scenarios where BGP contained within your home lab is beneficial for anything other than learning BGP. It's the routing protocol for the Internet. Its whole point is scaling globally, and - crucially - enabling making routing decisions that aren't just based on path weights. OSPF, IS-IS, EIGRP, whatever, they are all just path finding algorithms; OSPF is quite literally Dijkstra. That's great when you want to find the shortest or fastest path to somewhere, but that's not how the Internet works: it's quite reasonable for an operator to want to take the cheapest path (in terms of money), or to take the path that avoids specific foreign countries. BGP is expressive enough to write routing policy like that. You don't need that in your homelab, unless you want to learn BGP, either because you need to for work or to further your career, or because you're curious about it.
Running a few Kubernetes nodes with a network plane like Cilium that supports using BGP to inform your router about which container IP is on which node is a simple-ish one.
Not really, unless you have thousands of routes to manage across large numbers of gateways. Otherwise, running BGP inside your homelab is just a learning tool.
