If the Meunier links are credible and we do end up signing him, loaning Dalot to a club like Everton for 1-2 seasons would be a smart move, I think. This isn't to insinuate that they are a team that depends on loans — just that we seem to have a decent relationship with them, Marco Silva (a former fullback) could be a good coach for Dalot, and he would benefit from training/playing with Digne (who has developed into one the best fullbacks in the league), Coleman, Baines (if he stays at the club). A timely loan or sale + buy-back move with consistent playing time can be the making of a young defender — like Carvajal at Leverkusen or Hakimi this season at Dortmund, especially in terms of confidence and decision-making improvement.
Folks need to consider that Dalot is super inexperienced at first team level (with 30 first team appearances as starter or substitute at Porto and United combined), and should be nurtured properly because he has been one of the most highly-rated fullbacks in recent years: right from U-17 level, and is actually more developed than Cancelo (needed 2 loans), Pereira (who needed a 2 year loan at Nice), Semedo (was loaned to a Portuguese Second Division team) at a comparable age — and all three are among the Top 10 rightbacks in club football right now. Even Philipp freaking Lahm was loaned to Stuttgart for 2 seasons at age 20, and not every young defender takes to first team football like Alaba or De Ligt.