Unfortunately, you have to act within the confines of the program. If you had had rental income in 2019, you would have been able to enter the sale there and the passive losses would have been incorporated. They have to be taken into account and you can't adjust the sales price. This is why I am strongly suggesting that you keep the Form 8582 very safe.
From Form 8582 instructions.
Form 4797
If you sold assets from a passive activity or you sold an interest in your passive activity, all gains from the activity must be entered on the appropriate line of Form 4797.
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