This kind of implies that you're crunching and then 'recovering'. That may or may not be something you have any control over - there's a lot that goes into creating an unsustainable 'sprint', and probably 99.8% of it is not related to actual developers or code - but ideally you would be using these 'lulls' to try to pull stuff out of the next crunch so maybe it won't hurt so bad.
In reality, if I'm coming off of a bad crunch, I do anything I can do to avoid burnout. Sometimes that's 'fun' backlog items or research for future features or something else I'm excited about, sometimes it's studying for certs, sometimes it's cutting slack (@[email protected] watching Netflix feels familiar!). But again - whatever it takes to recharge my batteries and feel less bitter and shitty.
The most 'sure' sign that I'm coming off a crunch, though, is that I start reinforcing work/life boundaries. "It's 5p and I'm logging off and I'm not going to think about work shit willingly until tomorrow."
No this is great in and of itself - what I would tell you is to treat your github projects, even if you're the sole contributor, like you're working on a team. Checkout a feature branch, complete your code, then PR it into main/master/release/whatever, even if you're the one doing the code review for yourself. Even if you don't get to experience other devs (inevitably borking what you're working on) in the codebase at the same time, it'll give you a better idea of what the workflow should look like.
This all makes the SRE part more understandable and more within reach. I wouldn't lead with, "I don't have any dev experience"; I would lead with "I've been a software engineer for x years, specializing in atmospheric modeling." Whoever is interviewing you will probably dig and figure out that you were a solo developer, but....you were still a software dev, and the first job in this industry is way harder than the next couple. Lean into that - you have the job title, you have the resume, you're looking to take 'the next step' into SRE/DevOps, because as a solo-dev, you had to handle all that stuff yourself, and you figured out that you liked it and were good at it.
We've all been the new guy trying to break into the field - pay it forward after you land that first SRE gig.