Dry Yeast Starter

Hi folks

Haven't looked in for some time.  Hope everyone is well and coping with the worldly woes.

Have a question which I instinctively think I know the answer to but this being THE bread forum I feel sure someone will have already done it, got the T-Shirt and can give me the answer.

Question:

If I take a packet of dry yeast, mix with flour and water and keep feeding it in this way like a sourdough starter what do I end up with?

My assumption is that over time the constant addition of flour will gradually result in the natural yeasts in the flour overtaking the dry yeast strains that the mix started out with and thus I just end up with a conventional sourdough starter.

If so is there any way, domestically, to culture conventional dry yeast or indeed fresh baker's yeast?

Cheers and stay safe