The open source tools for the Silhouette work pretty well in my experience, there's a really well documented python library. You're right about the supplied software though, it works but it's unpleasant to use.
Yeah they also come up second hand pretty often. The supplied software works but is a bit of a chore to use However there's a python tool for sending it SVGs that works really well.
Can really recommend the Silhouette Cameo line of vinyl plotters (silhouette sells a pen adapter) for anyone who wants to buy a currently in production plotter that's much cheaper than the axidraw. I can't compare the two on performance as I haven't used an axidraw but my experience with the Silhouette Cameo plus has been positive
I'll throw in a vote for teaching yourself or using free resources and communities. Even if you go down the bootcamp route it is going to take a lot of self motivation and work outside of the bootcamp / afterwards in order to become job ready. Or at least do this to start with to make sure you like it.
I did this myself a few years years ago over lockdown. I had a lot of down time and worked on teaching myself web development full time 5 days a week for about a year. I was then able to land a job at a FAANG company through an apprenticeship scheme that they offer in the UK (I'm not sure if these kinds of schemes are available in the US) where I stayed for a year and a half and I am now working for a startup in a position I found through connections I made at my previous job. At the time I did have other offers for non-apprenticeship roles at other companies so don't let the absence of apprenticeships put you off if they aren't on offer in the US. The job market was definitely better when I was applying for my first job so the process might be more drawn out now. The main resource I used for self teaching was The Odin Project (https://www.theodinproject.com/). I also did a batch at The Recurse Center (https://www.recurse.com/) which was a great experience in general, especially for getting some hands on time working on projects with other people. I would say be curious, reach out to people who are working on things you find interesting to ask them for a chat and just persevere with the applications as you will definitely get a lot of rejections.
One more thing (might be UK specific as well) but I would check to see if there are any government funded bootcamps you might be able to get a place on. I know multiple people in the UK who got the job center to pay for them to do a bootcamp while they were on universal credit and now work in the industry.