Your comment glosses over a ton of critical details.
The most important of them being that even on such an old technology generation (180nm-110nm) no two fabs are so compatible that you can send a GDS designed for one of them to the other unless (a) one of them licensed their process from the other, like IBM/GloFo/Samsung back in the 2010s or (b) you planned for this in advance and designed a custom "least common denominator" process (like MOSIS SCMOS) to target which means making very large performance sacrifices. The (b) approach is much harder than it looks; I know of no examples other than MOSIS SCMOS, and in spite of being the pioneer experts at doing this they had a hard time at 180nm and failed on the following (90nm) generation.
The other, lesser, problem is that no foundry will let you even submit a GDS without signing their NDA. Even if you swear to them that you don't need their design rules for some reason. They don't care. NDA or no chips, not up for discussion. In fact, technically SkyWater still works this way -- to avoid the NDA you must submit through eFabless, not directly to the foundry (maybe this will change someday) and eFabless signed their NDA, then (obviously) negotiated a waiver. So saying "you can work around this problem that the only no-NDA foundry has by just going to another foundry" because there are no other no-NDA foundries, nor are there any on the horizon.
