I have been wondering the same thing myself. As the LLMs are currently constituted, they are almost certainly well beyond the means of even a maxed out 'home' computer.
However, I can't help wondering if it would be possible to create a LLM using Wolfram language that could run on a laptop. My current MacBook Pro has 64 Gbytes RAM, and 2 TByte storage, but current iterations can have more of both, to say nothing of the Mac Studio. I first ran Mathematica (version 1.1) on an SE/30 that had 8 Mbytes RAM (the minimum was 2.5), and that extra RAM almost doubled the cost of the computer -- but it was well worth it. In my opinion, current hardware capacity is being underutilized by Mathematica.
Creating a LLM would be beyond what could be done without linked servers, but running one should be possible. (?)
A useful first step would be to make the current neural net functionality use Apple's hardware, instead of requiring a NVIDIA GPU. Next, applying some of the multi-computational ideas from Stephen's physics project might be better than the current effort, which seems to be more 'brute force' than necessary.
I would not mind if the LLM 'specialized' in Wolfram Language code. Such specialization might require fewer resources, and would avoid a lot of issues with current LLMs. (In tests I've done, the LLM seems to make stuff up at least 50% of the time, which renders it useless for many use cases.)