> So, my question to this forum is: am I delusional to think that I can put together a program, under the freemium model, whereas my basic "tools" are out there, for free (open source license), for anyone to use; and then have certain "services" under the tiered subscription model

not delusional, but if you think everything else is a scam, what you will do and sell will be seen a scam by people like you (me). You might get yourself limited by being scrupulous whilst people that make a living out of it are not