The CEO/Founder wouldn't even consider a refactoring or cleanup session, let alone a full or partial rewrite. Only features drive sales, and we've sold so many things we don't have, so all he wanted was feature cram. Every so often, a VIP customer complained about some major use case that simply didn't work, so only in those cases was bug fixing permitted. And in those cases, the VIP customer would get a custom bespoke build made with the bug fixed. I was hired because the last person of my seniority could not cram features in fast enough and gave up in disgust.
They only got source control because I came in on a weekend, unpaid, to do it. I lasted a little over a year. Bootstrapped founder (and sole shareholder) eventually sold the company for ~$150M. Sometimes it seems there is no justice in the world :)
> This business unit has a pretty aggressive roadmap as management and HQ has no real understanding of these blockers. And post COVID, budget is really tight.
I've been at a company not unlike this... several MLOC of VB WinForms that was total spaghetti, but a highly successful app that brought in a lot of revenue. In our case the majority of the dev team was in agreement that the situation wasn't sustainable, and at first (meaning when I joined the company) we had engineering leadership who mostly agreed. They brought in several rounds of consultants to evaluate the code base and announced plans for a major modernization effort. But the consultants largely agreed with the dev team that the code was in such bad shape that it effectively needed a rewrite. At one point we did a prioritization and t-shirt sizing exercise and came up with _30 man years_ worth of items in the "critical tech debt" bucket. Apparently engineering leadership was not aligned with the C level suite about how much money they were willing to spend on this thing, because within the next year there was 100% turnover of management in the engineering org. A couple of (talented!) people who had been hired for the modernization effort left first, then the other engineers who knew the code base well followed. Last I heard the company was limping along relying on Eastern European and Indian contractors to keep the lights on.
In short OP, you can probably get some wins; maybe some major process improvements like using source control, maybe more minor things like introducing patterns or frameworks so that net new code isn't a total mess. But there is zero chance that you're to do anything like a rewrite or major refactoring without leadership understanding that they're in an unsustainable situation and a willingness from them to invest time and money to fix it.