yes. Crypto Trade costs affect portfolio performance, so the accuracy of prices in Fortopolio is sometimes not the same as prices on the market, but there are only a few differences, so I don't think that's a problem,
I think that regardless of the market prices, you can up to some extent minimize the risk of your assets in the portfolio so yes this is a fact that it is not a big problem but there is always a limit to the diversification.
there is a limit to the price diversification in the portfolio, so I always see my crypto asset price from the exchange directly, because if I look at the portfolio, I'm afraid the price isn't the same when on the exchange and makes my trade mess.
why don't you do the opposite, count the portfolio before our assets enter the exchange. calculate total assets in the form of "FIAT" before we use to buy crypto assets. It aims whether we really profit or not. Because crypto prices tend to be unstable. If only we count the total assets in the form of crypto then we trade and we think we get profit, but of course the main coin price goes down, then when we exchange to "FIAT", we realize that the profit is only a bit from whole assets we use for trade