To be clear, I've certainly met people in their 20s that have senior-level ability, but they are by far the exception.
In fact, the 6-8 years of experience you quote is far higher than I would have guessed if you asked me when the average company (incorrectly) starts handing out "senior" titles.
Jobs like presales engineers have higher salaries than developers, require 15+ years experience (dev preferred) and excellent soft skills.
Move to a market where your skills are in high demand and focus on middle/business and back end development. Or better yet, embedded systems development.
I've been at this for 25 years and IMO, the further down the call stack you go the more your cumulative years of experience are an asset.
This doesn't mean you can stop learning new tech, it just means the trends in those lower layers seem to be more sustained and of a longer duration.
Given your struggles to get a job and your very valuable experience, what's holding you back from going as a contractor / setting up your own shop?
Can't afford to live in the US anymore but Mexico is working out pretty well.
Heck, to the right client, that one i860 or C80 programmer might be worth gold. Either that, or just do a highly competent job at embedded programming generally.
Joining a bootcamp makes it look like you are new to the field and will settle for an entry-level salary. This is a very extreme solution, but might help you solve this problem for several years.
I feel bad for saying this, but my advice is to dye your hair, join a gym and take some years of your Facebook profile.
Try to save some money to buy a car to do Uber, start a small IT consulting firm or get a job teaching. Most people will advice mild patches but they dont know what it's like to run out of money. I feel your pain.
Being somewhat older than you, but bored, I think about taking up the oar again. My problem doubles down on yours in that my background is all in products with an expensive hardware component or workstation software, neither appears to be a growth industry.
Aside from the inevitable well-meaning advice to become some sort of 'project manager', etc. I wonder if it makes any sense to hit the .gov job markets at all.
Has anyone done that at an advanced age?