As a profitable company, assuming they have competent developers, they could get what they need to built. Figma's "secret sauce" is using WebAssembly [1] to do their rendering.
The reason I harp is that everybody is complaining about the demise of Figma while completely ignoring its demise was precipitated by massive venture capital investment.
[1] https://www.figma.com/blog/webassembly-cut-figmas-load-time-...
If all it took to build a figma was to plug in web assembly, I'm pretty sure Adobe would have pocketed the $20B and built it themselves. There's a reason they didn't. They tried and they couldn't do it.
> There's a reason they didn't. They tried and they couldn't do it.
Time, mindshare, and brand. They could absolutely do it (all of their apps are insanely complex), but it's far faster to cut a check and wipe out your primary competitor and eliminate the cash flow leak (which based on that number, they estimated would be greater than their purchase price for Figma).
Also I think the multiplayer web native feature that is at the core of Figma is not trivial. It is possible that you can find a very talented small team of engineers to get it done but the motivation here needs to be more than just financial upside.