- Don't talk to the company at all. Don't explain anything. Don't say anything. The burden of proof is on them, not you. The more you talk, the more you are putting yourself at risk because the whole "Anything you say can be used against you" is really a thing. Even if you want to help them, don't.
- Being quiet is not an admission of guilt. Let them say whatever they want. Let them try to make you feel bad. You just don't respond with anything.
- Document everything you can in terms of your departure, timeline, what events occurred few weeks/days before your departure from the company. Write everything down. You may forget a few things later. Be specific.
- Stop talking to those other devs as well, at least about this issue. Better to not talk to them at all. Be very quiet.
Best case, the employer is just trying to find a scapegoat to blame for their own failures. They may move on if you don't fall for their blame game. Worst case, they are preparing legal action against you. In both cases, do not talk to them or anyone else about this issue except a lawyer who represents you.
EDIT: Btw, if anyone hasn't seen this video [0] at all, watch it. It is a great explanation by an attorney on why you should never talk to law enforcement without an attorney. Even if you are innocent and mean well.
They have accused you of a crime and if they have enough to convince a DA, you will have the government aiming for a conviction, along with all the resources they have.
Privately document everything you did from the time things started going bad at the company. Be as detailed as possible, if you have any emails preserve them, but don't access any of their systems to do so. If they send you any communication trying to blame you get legal representation and give them everything you just documented. Do not make anything public, don't write blog posts about it, keep it professional and quiet. If they don't do the same then find an attorney to help you pursue them. Do not even visit their website.
I also wouldn't overreact initially, the reality is that companies going through troubles like this operate in chaos most of the time and are knee jerk reacting to many things at once so they are their own worst enemy and will hasten their own demise. Let them tie themselves in knots not you.
Outside of the above and as a general rule, don't interact with them or give them any information at this point, anything you say can be twisted into "facts" to trap you. You are better off keeping your mouth shut and just letting them spin. If they reach out blaming you the only thing I'd due is reply once something to the affect that "I left your employment and have had no access to any of your material, systems or IP since the day I left and only wish the company the best." You aren't giving them a defensive response, you aren't stating any detailed facts they can try and tweak to fit a narrative they want, you are simply stating you left and left all their materials there. Of course if this isn't true you should rethink the reply and likely just get an attorney, but just some basic advice. Also beware of any existing/former employees reaching out, even "friendly" where they ask you any questions or try to get you to detail anything.
caveat on all this: I'm not a lawyer and if you did something shady you need to approach this very differently.
Contact a lawyer, asap; if your colleagues are being led to believe this was you, this is defamation and may be affecting your ability to find new employment.
It sounds like your company is quite a piece of work, but if they are disorganized as you say at so many levels, it just sounds like them using you as a scapegoat. For a few months after someone leaves, everyone blames that person anyway - they can't fight back. That part is normal.
But assuming you are in the US, and they are potentially defaming you as individuals, then in my view deferring to an attorney puts everyone on edge and seals lips, whereas it seems very unlikely that an apparently failing company will expend dwindling resources and runway chasing a civil suit for an unemployed engineer.
Personally, I'd let them run their mouths and capture what you can. You could even try to be helpful by questioning what problems they're having and why they think it's you just to have them make further statements that either bolster a defence or give you ammunition for defamation proceedings should you wish to.
Don't fret too much (all assuming you've done nothing wrong). They're likely just stressed to the gills with a failing business in a pandemic so not acting rationally.
Today.
Now.
Get off HackerNews.
Call a lawyer.
Did I mention the lawyer part?