You have got some great recommendations. IMO, you can’t go wrong with Sage + Niche combo.
FWIW, the following are the observations based on my daughter’s experience. She was in your situation 2 years ago.
She has a Bambino, a hand grinder and now Niche. She uses Tesco Ashbeck and buys some very nice coffee. She is very happy, although feels the difference in taste when they drink the same black and the flat white pulled from our Evo at home.
Their experience suggests grinder, good beans and then machine are the orders of importance coupled with filter water. For them, a) dialling in beans are fine as long as they are medium and the south of it; b) struggles to dial-in light roasts for flat whites without choking the machine c) steaming can be a little more powerful; and, d) I often pull some espressos and decafs on her machine tamping a little harder. It can choke the machine, but I get some great shots - this is someone who is used to the coffee from Evo.
She is already sucked into the rabbit hole. For her, temperature stability, light roasts, PI and pressure surfing are important. I can’t imagine she will be content with anything other than at least Bianca, if not Decent, LM or Evo. There is a risk the latter can easily walk away from my home.
In short, Sage and Niche are great kits to start with, provided you cover the other requirements. Please buy what you are comfortable with. Otherwise, buy well and forget upgrading for a long time. GL and welcome to the rabbit hole. 😊