I am not sure this is even desirable: I think you should have to do maximal efforts in some form or another on a regular basis in training. Whether that takes the form of a ramp test or a max effort on a Strava segment doesn’t matter. You should know what a max effort feels like.
When I entered my first race in 2019 it helped me tremendously that I knew I could do the efforts asked of me to participate, precisely because I did them while training.
You’ll get similar error bars with other methods to estimate FTP. @jjmc summarized his thoughts quite well in a recent thread. E. g. when doing a 20-minute test, you are asked to subtract 5–15 %. And a by-the-book TTE requires you to do a ramp test first so that you know what power to shoot for. Personally, I don’t think you can do much better in a regular setting (i. e. not in a lab) than the ramp test or the 20-minute test, and that the error bars are quite substantial, probably a lower bound is 5 %. In my experience a change of even 2 % in set-FTP (to scale workouts) can mean the difference between comfortably finishing and breaking down with e. g. difficult threshold workouts.
But IMHO that isn’t an issue if you keep your brain switched on, listen to your body and tweak the number your favorite test method has spit out using your experience as an athlete who is aware of his body.