A fun idea indeed! This is actually quite doable today (though not necessarily advisable). No fancy UI/UX is necessary though. Rather we can just a generate a big list of addresses. Then you can use the "send to many" feature in a wallet of your choosing you can send sats to future miners!
The locking script is a simple anyone can spend script <blockheight> OP_CHECKLOCKTIMEVERIFY When we wrap this script in a pay2sh or pay2wsh output (so that any transactions sending funds to it are still considered standard), then this means that future miners interested in spending such an output would need to know about it first or how to derive/check similar addresses, but it is not hard for them to do so.
Here is the pay2wsh address for a blockheight that will unlock somewhere near year 2140:
block number 6973063 (approximately end of year 2140): bc1qmqckte0sfhh8xyc6v7zswrs5mpjrrf2f5frwe2yz68lyy253m7qshzrdqn
Here are some more addresses:
block number 7025623 (approximately end of year 2141): bc1que50q4j3rkz782y8m8s6xqzra32j8qmf0tsxaltlhayy6jr68phqekpu4r block number 7078183 (approximately end of year 2142): bc1qxfagwc0v0gytcjy7zmq6wr73fndk7ltevwmak97xyd07q6fru8hs5vufs7 block number 7130743 (approximately end of year 2143): bc1q4ldz0stpet6qf0qzdqqswrhuhhw0hyj6ezxskh3q0785cwypn3kqmd6q42 block number 7183303 (approximately end of year 2144): bc1q7yvzu937xx4j5jvrr08qxu9ut9jmx82nk3qhltjk0tjt6qk7rkgs55s0eg block number 7235863 (approximately end of year 2145): bc1qdhwu4x34z3yksq4ca4fnf2d7hp2nw3d8ne6va25j36f5p4u7kk0stm74ca block number 7288423 (approximately end of year 2146): bc1qkwsj47mucut9cvcf66lwn8tzc75lzz2wdagqnzsl0vd0huee5ktqma3cke block number 7340983 (approximately end of year 2147): bc1qw99zdp6z7xsxdk40lgu56582s8n5vhmga5hw5kzrtmq73v7r5weq4rw3p9 block number 7393543 (approximately end of year 2148): bc1qp7dc8849nkcpz35pmlj5a7tk6tj0r4t5yee8j8cr4fuqehxx5gyq547tzs block number 7446103 (approximately end of year 2149): bc1qpaqd826nsdm503t3wv6pf0dfgy9f3adrpj865e3euqayp35443zq7es949 block number 7498663 (approximately end of year 2150): bc1qax770e6u4x08nhslue3chy4wtxt5rcll53542smk4qcwsyvzuk5qwcne09 block number 7551223 (approximately end of year 2151): bc1qqk4zw2652k5vg3ujxnndwc2ljphkjdgrl7u4k8p47dvm89wgga8qfsvs2z block number 7603783 (approximately end of year 2152): bc1qzstkpf9pdqzvtpfr4v6mtkh3j4ssy7cyrmtlak223fga0yf4d94qttfujz block number 7656343 (approximately end of year 2153): bc1qfkjyaezp03lnn85f42hp8zs0449zn0z7m0wsfxcyz6a6l7tt8wusenqycp block number 7708903 (approximately end of year 2154): bc1ql2ycs7gudtcjpmajggkq2xzl6y34dheurgnd8ypaj33clhuahgzsz3ewl8 block number 7761463 (approximately end of year 2155): bc1qu9p2ydctxnvvjaektpqx5emfusez7343f68gu0hdfsr6r8ec993qe3k5m0 block number 7814023 (approximately end of year 2156): bc1qaqs0sc7d2a70737kmsv369zefmrr4jp9wn0xt4z6a4spd65c5d6s6d5q90 block number 7866583 (approximately end of year 2157): bc1qv2k3p0dt5kdj5qdeslqhzkk0cl4jf09f7tyd72tuhv50ancqqgrsntcejk block number 7919143 (approximately end of year 2158): bc1q63s3y5c0d2fw32w9fkp7dzwfk3srz5u25t9dez4uea3uz0wh6lwqe5wumm block number 7971703 (approximately end of year 2159): bc1qulvu323repmtena46snlem2md35qj2gn7t7etnjr3lqmsw0l7a0sdlqum3
Note: I did not have a chance to double check these. You should probably not send money to these addresses. Rather I just wanted to demonstrate that it would not be hard to create such a list, either statically or on-the-fly. There are also other types of addresses which would likely be cheaper from a fee standpoint.