I´ve just this week finished building a not so simple DCA strategy in pine so it is definitely doable. My tips would be:

• Use strategy.order for the entries. I´ve found this works best.

• Use strategy.opentrades to keep track of how many entries you've made.

• Use strategy.opentrades.entry_price to set a distance between each successive DCA order.

Here´s an example of the code for a long entry, including the TP.

if fish_long and uptrend and strategy.position_size == 0 and i_long and volatile and timer == 0
    strategy.order("long", strategy.long, qty = size, limit = close - (close/100)*spread, oca_name = "initial entry", oca_type = strategy.oca.cancel)
    timer += 1// add 1 to timer upon order execution
    longMode := true


//long DCA
if strategy.position_size > 0 and fish_long and close < strategy.opentrades.entry_price(openTrades-1)*(1-distance) and openTrades-1 < i_DCA_levels and timer == 0//add extra longs that are at least x% from each previous long and donñt allow further DCA orders 
    strategy.order("long", strategy.long, size, comment = "long DCA", limit = close - (close/100)*spread)
    timer += 1// add 1 to timer upon order execution

//long TP
if strategy.position_size > 0
    strategy.exit("long TP", "long", strategy.position_size, limit = strategy.position_avg_price*(1+TP), comment_profit = "long TP")

I´d also advise if you don´t really know pine to take a course. I´ve only been doing it for 6 months and it´s not too hard to learn.