If both hearing aids are the same brand, you should be able to get that brand’s streamer and be able to use just one for both sets of hearing aids.
If you use (a) bluetooth streamer(s) you’ll probably need a streamer for each set, although there are more sophisticated streamers out there that might do both sets. But there tends to be an issue where there is a time difference between what you see on TV and what you hear (called latency) which is unacceptable in most cases. Some TVs have an adjustment to try to sync them. But it is often an issue.
I bought a streamer off Ebay about a year ago, and it cost a lot less than the retail price that way. It works fine and I use it much of the day for streaming zoom and google meet meetings from my macbook pro.
WH