Save the money on a new RW, that is on the same and top level like Sancho or Gnabry. To compete with City, Pool and B.Munchen.
Grealish is really good. But he is not on top level. United need a specialist wide player. So United can develop Greenwood as CF for full time. Greenwood as RW in need, when United current RW are not good.
A RW and A CM are top priority. Grealish is a nr.10, LW or LCM.
There a few who are on Sancho and Gnabry level. On Grealish level, there are many out there in the world. Spend and work your time to get unique one. First. If not, then plan B, C.
Fix your weakest point first. Last summer lesson. United didn’t buy a nr.10 last summer and no new RW. It lead to United were close to be far away and out of reach for top 4. Luckily Bruno arrive 1.Feb as a new nr.10 and save Ole and United season. Don’t repeat the mistake. You fix the biggest and most important problem of your car first. Then 2nd and 3 rd. So that are my advice.