Is cost a consideration? Many folks use the ZWO 60mm guide scope, it may have a cost advantage over those other two. Usually available from Bintel.
There are also a range of new Mini-guidescope, made by Orion and ZWO, which are well suited to the small cameras from ASI like the 290 mini. If you main scope has a focal length of just 550mm, a mini guide scope might be a good match. The mini guide scopes usually just slide into a finder scope bracket, which is another plus in that you Don't need a top rail to mount them.
Stay away from OAG setups when your just starting out.
https://www.bintel.com.au/product/or...v=322b26af01d5
https://www.bintel.com.au/product/zw...v=322b26af01d5
Note the low stock levels on these miniguidescopes, they are very popular now and sell out quickly.
And as far as finding more stars goes, your best bet is to buy a good sensitive guide camera like the ASI290mini, but they are not cheap. The ASI120mini is much cheaper.