I have created a couple of small stores and being FOSS lover myself I can give some advice.
First, your options are WooCommerce or PrestaShop and alike. Don't fall into being idealist and JS-free now, because there is no software suite on the market that is going to give you that. Except payment provider, it can be done, but you would need to write e-commerce software from scratch yourself and I guess this is not in your capacity. Both of them have no trackers, just choose a lightweight theme because some third-party themes include fonts or scripts from Google-alike because of lazyness. You can use build-in ones and modify them. PrestaShop themes are much easier to modify, because those are Twig templates instead of full PHP scripts. WooCommerce is GPL so plugins must be free software too, but many of them are from shitty devs who provide only obfuscated scripts, so you must check each plugin by yourself. PrestaShop plugins are more often proprietary, but you need much less of them, as almost everything internal is out-of-the-box. With Presta you need payment provider plugin and basically that's it, while on Woo every single thing like different tax for a region would require a web of plugins.
After some time with both my scheme is: WooCommerce if you have a blog-style website and just want to sell something as a bonus. PrestaShop if you start a real small or big businesses and selling is the primary goal.
As for VPN, what can I say other than this is not sustainable. You are literally selling stuff with your name so there is no privacy or freedom benefit with additional routing. Just get an ISP offering a public IP (not beind a NAT) and open a firewall port. Or if you cannot do that, rent a VPS. I don't see a point in anonymity here, pure clearnet is more than enough for shopping for physical thighs.
And I say this as a quite hard level FOSS person. My machines are all on Linux, being able to connect Yggdrasil, I2P, Tor at once, with seedbox running 24/7 and tracker blockers everywhere.
In commerce, there is no point to fight here, just use the popular thing and not make it worse than vanilla, that's it.