jm hmwyda - BSV alternativesMVI found two possible alternatives:
https://member.cash is BCH-based, but it allows to post long text, it splits text into several transactions.
https://www.myetherwallet.com is well known ETH wallet. It works in browser and allows to set arbitrary "data" field while sending transactions.
You can try them out and share your experience here.
https://whatsonchain.com/tx/cca4d5e22c5cd5dce89c61e5efe581569ddcb49bd98a445c143a41c5cf1b4b0c