I’ve been going through this recently too and found a solution that works amazingly well for me.
I use IEMs and this is my set up, which gives me a great sound but also makes me feel like I’m on stage and not isolated. Nothing groundbreaking!
I use my own mixing desk and use 5 channels. What’s important for me here is my two stereo DI boxes, hopefully this won’t confuse things.
Channels 1&2 - I take my stereo out from my keyboard into my stereo DI, then from my DI into these channels (reasons for DI later)
Channels 3&4 - I have 2 condenser mics behind me high above my head to give me a stereo on stage sound. Also great for gigs where the drums aren’t mic’d. Mic placement for these are yet to be experimented with but already working well. They were only £45!
I pan 1&2 to L & R and the same with 3&4. Not a hard pan mind.
Channel 5 I take a monitor mix from the main desk where I get the mix I ask for. Mostly Vox and gtr. This gives me a great sound, complete control and also gives me an ambient sound without killing my ears.
The second DI I use takes the ‘Link’ from the first DI, then feeds out to the main desk. This gives me a feed to my desk and a feed to the main desk.
Reason or the two DIs. Many, including a better signal. But the main reason is my condenser mics require phantom power. So DI 1 protects my keyboards from that. The second DI is to protect from potential accidental phantom power usage from the main desk.
I hope that makes sense, not as complicated as it sounds and works great for me. I’m far from an expert here so others may think my solution is nutty.