From working in a somewhat related discipline, the PDKs for the high end nodes (think tsmc N16 and lower) are quite hard to obtain and require your org to pass security audit. In addition to that the cadence licenses are priced very much for a big-org rather than a startup.

Does your chip absolutely need a modern node? I'm assuming you've seen the open source skywater pdk, but here it is just in case. https://github.com/google/skywater-pdk