Well, it’s a two levels problem. First you have to decide which indices you want to replicate in your portfolio. Second, you decide which funds to take for this.
There are also other levels. Most importantly, consider all your stocks holdings, no matter which broker, as a part of one overall stocks portfolio. Then you can do things like this:
Together with fixed income holdings (cash, bonds, fixed term deposits), they constute a stocks+fixed income portfolio that you can control. Add your pension savings, real estate, crypto and that picture that you got from your grandma, minus all debts, and this is your net worth, or, as I and some other prefer, net wealth.
All these levels were extensively discussed in this forum and where not.