Logseq already support extended Markdown table syntax. I use sites like https://www.tablesgenerator.com/markdown_tables to help create the markdown table syntax from spreadsheet/webpage when needed. It’s also simple enough to just type from scratch. Example GFM Markdown Table text:
| Tables | Are | Cool |
|----------|:-------------:|------:|
| col 1 is | left-aligned | $1600 |
| col 2 is | centered | $12 |
| col 3 is | right-aligned | $1 |
It’s shown as below in Logseq v0.3.2
Unfortunately, Logseq doesn’t do GFM Markdown Table alignment syntax.