"I did a comparison check of the Vaneck Gold ETF (ASX:GXD)...

"I did a comparison check of the Vaneck Gold ETF (ASX:GXD) versus NST over the last 3 years.
...since mid 2018 NST has underperformed the ASX gold stock index by ~12%."

I have not been able to confirm the big underperformance by NST that you assert.
Obviously the result will vary depending on the precise period considered, but once the difference in dividends is taken into account, there is no underperformance by NST relative to the GDX etf.

Indeed, over the three year period from 16 Jul 2018 to 16 Jul 2021, after accounting for franking credits, the total return from NST beat the GDX etf by 2.2%. See table below.

Also, along the way, there was the opportunity to participate in the share purchase plan in Jan 2020 at $9.00, which shares are still in the money.

I agree the result from NST over this period is not all that exciting but nor is it as dismal as your post suggests.
Meanwhile the company has bulked up enough to make it into the ASX50.

This is not a comment on whether any CEO should be paid $34m.
I have mixed feelings about that.

Cheers

	NST	div	franking %			ASX.GDX	div	franking %
16/07/2018	$7.11				16/07/2018	$29.68
16/07/2021	$10.73				16/07/2021	$46.85
Price gain	50.9%				Price gain	57.9%
6/09/2018		$0.050	100%		21/12/2018		$0.1241	0%
13/03/2019		$0.060	100%		24/12/2019		$0.2340	0%
29/10/2019		$0.075	100%		22/12/2020		$0.2125	0%
6/03/2020		$0.075	100%
8/09/2020		$0.195	100%
8/03/2021		$0.095	100%
total div yield		7.7%			total div yield		1.9%
gain + div		58.6%			gain + div		59.8%
gain+div grossed up		62.0%			gain+div grossed up		59.8%