I'm aware that you once implemented Elasticsearch Plugin but later removed it. That's ok; the decision is completely understandable. And I'm happy to pay some bucks to elastic.co.

Now, how can I use Elasticsearch (on elastic.co) seamlessly along with Postgres on Railway?

I found elastic's official integration guide to use JDBC, but it looks complicated enough to give up.

Then I found ZomboDB. It looks to solve the problem. I went to their installation guide. However, I don't know how to use it with Railway. As I'm rather a frontend dev, I don't want to learn Postgres from scratch.

So why not add ZomboDB to your pre-installed PostgreSQL extensions lineup, along with Timescale and PostGIS? Please consider.