This has been simplified by transaction time lock you can read how to set up using this method by TryNinja
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You have mentioned some good topics, but after doing some research, I found out that this should not be practiced or our first priority to lock funds for like 5o r 10 years. specifically with this coinb.in website. You should read the following theads:
1:There's someone who tested it recently, had a few issue but in the end, it worked.
Some of the issues includes:
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2:if you really feel the need for the timelock transaction types then the best solution is that you go to .............
You have shared some best topics to read about time-lock and thanks for them as I was unaware of these topics. Plus I think, what Op is asking here is to use some application that can do this work (of course a wallet app). And of course that should be open-source and etc. etc.
I have one question (as newbie) why we will trust those new smart apps and why we even trust this coinb.in website as what metrices make them our first priority. To be honest I little afraid to lock my BTC for like 5 or 10 years. And I hope only inheritance related cases needed these types of functions. And I also doubt if anyone really have used these feature provided by any of the platform for inheritance purposes.
If not, then I think currently the market for such apps will be less as their are less people (young people) who are not married and not looking for solutions like these ( of locking transactions for 10 years). But if some smart wallet comes now and by time that wallet will get some decent trust by the Legendries.