Hi @geo.chiv.george I replied to a similar post here: Will my current domain's google SEO rankings be affected switching to Bubble?
I know from reading the forum announcements that Bubble are really aware of SEO challenges and this is defintey something you should be concerned about!
Basically the thing you want to do is make sure that you recreate the links and content as much as possible for the first step. The reason behind that is that your website probably has alot of backlinks and authority in googles eyes to be ranking number 1 spots. It also probably means that your website has alot of relevant content for those keywords.
So what I would do is blueprint your entire sites links (this would be much easier if you have a sitemap to work from which from a quick google search about shopify shows it should be on http://your-url/sitemap.xml . From there I would work on creating all the links on bubble and start filling the pages with content that matches your content on shopify (this includes recreating the H1,H2,H3,Hx tags that you are using in the content, the alt tags on the images, the actual text content etc).
Once you have that all sorted I would then use some onpage SEO tools to see if the content is as relevant as your current site is you may already have a tool but you could use something like https://moz.com/tools/onpage-grader doesnt really matter which one just make sure the grade is the same or better than your current site.
“technical SEO” is also a big factor nowadays and that basically boils down to how well optimised your site is, is it mobile responsive etc, how fast it loads. So you will want to make sure that all of that is in place too. Test your site speed with something like https://tools.pingdom.com/ and compare both the bubble site and your current site to make sure the site speeds are the same or better.
Once you are happy with that I would then just double check everything else making sure you have all those relevant links recreated etc and then make the move.
Unfortunately whenever you move your site you are always at risk of rankings dropping and google is a fickle beast but the chances are if you have great content and are providing a useful service / information and you recreate those pages which have all those juicy backlinks the chances are you’ll be fine and will bounce back if there are any rank droppings And like you said if you can ultimately deliver a better service thats going to stand the test of time then ultimately its going to make for a better site that more people will visit and want to link to anyway giving you much better rankings than staying with a site that you don’t feel you can update and improve on.
Hope that helps!