Treadmills are a marmite experience.
Some love them and use them a lot.
Others will say they actively degrade good running form.
I’m a shit runner so can’t comment!
I have one and find I can’t get anywhere near my usual outside pace on a treadmill (or at least sustain it). I much prefer running outside (when my mojo allows).
But if you do get one, I found zwift running pretty good. They have various interval sessions. You use a foot pod [c £50) or some weird thing that sits on your treadmill and measures belt speed to track the pace but the price of a decent treadmill is by far the biggest barrier. Can’t speak for others but I have a 5 year old sole fitness f85 still going very strong (although I’m guessing I’m not the most demanding of customers!).
Good luck and happy miles if you do decide to take the plunge!
(Although I can confidently add if you buy some winter kit the early morning dark winter runs are the best…no one about, 100% meditative experiences…I remember listening to “the sound of silence” cover by disturbed in the dead of night with the only light being from my head torch…magical…beats a treadmill any day!).