There is no end to the gifts suitable for the other party's parents. I think as long as you can show your filial piety, it's fine. You can give jewelry or practical items suitable for the elders.
First, I want to recommend you a gift suitable for the other party's mother. I think the best one is this sterling silver bracelet engraved with the word "Fu". Silver jewelry is almost exclusive to the elderly because they think it will bring them good luck. The silver bracelet with the word "Fu" is to send blessings and luck, and the elders will be happy to receive it.
Second, if you want to give it to the other party's father, you can give a wallet, watch, belt, etc. Here I recommend you a wallet and belt set, which is made of high-grade materials, first-class workmanship and very practical. It is a thoughtful choice.
Third, the best gift for the elderly is the gratitude and recognition of their children. On the special day of engagement, give each of the other party's parents a pair of towels to thank the father and the mother for their upbringing and happiness.